diff --git a/api/build.gradle b/api/build.gradle
index 1060a0a..01c890a 100644
--- a/api/build.gradle
+++ b/api/build.gradle
@@ -8,7 +8,7 @@ repositories {
 
 dependencies {
     // https://archiva.jessebrault.com/#artifact/com.jessebrault.gst/lib
-    implementation 'com.jessebrault.gst:lib:0.0.3'
+    implementation 'com.jessebrault.gst:lib:0.0.5'
 
     // https://mvnrepository.com/artifact/org.apache.groovy/groovy-templates
     implementation 'org.apache.groovy:groovy-templates:4.0.12'
diff --git a/api/src/main/groovy/com/jessebrault/ssg/BuildScriptBasedStaticSiteGenerator.groovy b/api/src/main/groovy/com/jessebrault/ssg/BuildScriptBasedStaticSiteGenerator.groovy
index 4fde512..a6aa702 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/BuildScriptBasedStaticSiteGenerator.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/BuildScriptBasedStaticSiteGenerator.groovy
@@ -2,7 +2,7 @@ package com.jessebrault.ssg
 
 import com.jessebrault.ssg.buildscript.Build
 import com.jessebrault.ssg.buildscript.BuildScriptConfiguratorFactory
-import com.jessebrault.ssg.buildscript.BuildScripts
+import com.jessebrault.ssg.buildscript.BuildScriptRunner
 import com.jessebrault.ssg.util.Diagnostic
 import org.jetbrains.annotations.Nullable
 import org.slf4j.Logger
@@ -18,45 +18,50 @@ final class BuildScriptBasedStaticSiteGenerator implements StaticSiteGenerator {
     private static final Marker enter = MarkerFactory.getMarker('enter')
     private static final Marker exit = MarkerFactory.getMarker('exit')
 
-    private final GroovyScriptEngine engine
-    private final Collection<BuildScriptConfiguratorFactory> configuratorFactories
     private final @Nullable File buildScript
-    private final Map<String, Object> scriptArgs
     private final Collection<Build> builds = []
 
     private boolean ranBuildScript = false
+    private GroovyClassLoader buildScriptClassLoader
 
+    /**
+     * @param buildScriptClassLoaderUrls the urls to pass to the buildScriptRunner's GroovyClassLoader.
+     *          These should include the URL needed to find the given buildScript file, if present, as
+     *          well as any script dependencies (such as the buildSrc dir).
+     * @param buildScript The buildScript File, may be <code>null</code>.
+     */
     BuildScriptBasedStaticSiteGenerator(
-            GroovyScriptEngine engine,
-            Collection<BuildScriptConfiguratorFactory> configuratorFactories = [],
-            @Nullable File buildScript = null,
-            Map<String, Object> scriptArgs = [:]
+            Collection<URL> buildScriptClassLoaderUrls,
+            @Nullable File buildScript = null
     ) {
-        this.engine = engine
-        this.configuratorFactories = configuratorFactories
         this.buildScript = buildScript
-        this.scriptArgs = scriptArgs
     }
 
-    private void runBuildScript() {
-        logger.trace(enter, '')
+    private void runBuildScript(
+            Collection<BuildScriptConfiguratorFactory> configuratorFactories,
+            Map<String, Object> buildScriptArgs
+    ) {
+        logger.trace(enter, 'configuratorFactories: {}, buildScriptArgs: {}', configuratorFactories, buildScriptArgs)
 
         if (this.buildScript == null) {
             logger.info('no specified build script; using defaults')
-            def result = BuildScripts.runBuildScript { base ->
-                this.configuratorFactories.each {
+            def result = BuildScriptRunner.runClosureScript { base ->
+                configuratorFactories.each {
                     it.get().accept(base)
                 }
             }
             this.builds.addAll(result)
         } else if (this.buildScript.exists() && this.buildScript.isFile()) {
             logger.info('running buildScript: {}', this.buildScript)
-            def result = BuildScripts.runBuildScript(
+            def buildScriptRunner = new BuildScriptRunner([
+                    this.buildScript.parentFile.toURI().toURL()
+            ])
+            this.buildScriptClassLoader = buildScriptRunner.getBuildScriptClassLoader()
+            def result = buildScriptRunner.runBuildScript(
                     this.buildScript.name,
-                    this.engine,
-                    [args: this.scriptArgs]
+                    [args: buildScriptArgs]
             ) { base ->
-                this.configuratorFactories.each { it.get().accept(base) }
+                configuratorFactories.each { it.get().accept(base) }
             }
             this.builds.addAll(result)
         } else {
@@ -67,12 +72,27 @@ final class BuildScriptBasedStaticSiteGenerator implements StaticSiteGenerator {
         logger.trace(exit, '')
     }
 
+    /**
+     * @return The classLoader used to load the buildScript.
+     * @throws NullPointerException if the buildScriptRunner was not initialized yet (make sure to call
+     *          {@link #doBuild} first).
+     */
+    GroovyClassLoader getBuildScriptClassLoader() {
+        Objects.requireNonNull(this.buildScriptClassLoader)
+    }
+
+    // TODO: cache
     @Override
-    boolean doBuild(String buildName, Consumer<Collection<Diagnostic>> diagnosticsConsumer = { }) {
+    boolean doBuild(
+            String buildName,
+            Collection<BuildScriptConfiguratorFactory> configuratorFactories,
+            Map<String, Object> buildScriptArgs,
+            Consumer<Collection<Diagnostic>> diagnosticsConsumer
+    ) {
         logger.trace(enter, 'buildName: {}, diagnosticsConsumer: {}', buildName, diagnosticsConsumer)
 
         if (!this.ranBuildScript) {
-            this.runBuildScript()
+            this.runBuildScript(configuratorFactories, buildScriptArgs)
         }
 
         def build = this.builds.find { it.name == buildName }
diff --git a/api/src/main/groovy/com/jessebrault/ssg/StaticSiteGenerator.groovy b/api/src/main/groovy/com/jessebrault/ssg/StaticSiteGenerator.groovy
index 43240f9..f9b0e70 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/StaticSiteGenerator.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/StaticSiteGenerator.groovy
@@ -1,9 +1,15 @@
 package com.jessebrault.ssg
 
+import com.jessebrault.ssg.buildscript.BuildScriptConfiguratorFactory
 import com.jessebrault.ssg.util.Diagnostic
 
 import java.util.function.Consumer
 
 interface StaticSiteGenerator {
-    boolean doBuild(String buildName, Consumer<Collection<Diagnostic>> diagnosticsConsumer)
+    boolean doBuild(
+            String buildName,
+            Collection<BuildScriptConfiguratorFactory> configuratorFactories,
+            Map<String, Object> buildScriptArgs,
+            Consumer<Collection<Diagnostic>> diagnosticsConsumer
+    )
 }
\ No newline at end of file
diff --git a/api/src/main/groovy/com/jessebrault/ssg/buildscript/BuildScriptRunner.groovy b/api/src/main/groovy/com/jessebrault/ssg/buildscript/BuildScriptRunner.groovy
new file mode 100644
index 0000000..e4630af
--- /dev/null
+++ b/api/src/main/groovy/com/jessebrault/ssg/buildscript/BuildScriptRunner.groovy
@@ -0,0 +1,71 @@
+package com.jessebrault.ssg.buildscript
+
+import com.jessebrault.ssg.util.ExtensionUtil
+import groovy.transform.NullCheck
+import groovy.transform.stc.ClosureParams
+import groovy.transform.stc.SimpleType
+import org.codehaus.groovy.control.CompilerConfiguration
+
+import java.util.function.Consumer
+
+@NullCheck
+final class BuildScriptRunner {
+
+    private static Collection<Build> runBase(BuildScriptBase base) {
+        base.run()
+        BuildSpecUtil.getBuilds(base.getBuildSpecs())
+    }
+
+    static Collection<Build> runClosureScript(
+            @DelegatesTo(value = BuildScriptBase, strategy = Closure.DELEGATE_FIRST)
+            @ClosureParams(value = SimpleType, options = 'com.jessebrault.ssg.buildscript.BuildScriptBase')
+            Closure<?> scriptBody
+    ) {
+        def base = new BuildScriptBase() {
+
+            @Override
+            Object run() {
+                scriptBody.delegate = this
+                scriptBody.resolveStrategy = Closure.DELEGATE_FIRST
+                scriptBody.call(this)
+            }
+
+        }
+        runBase(base)
+    }
+
+    private final GroovyClassLoader buildScriptClassLoader
+
+    BuildScriptRunner(Collection<URL> classLoaderUrls) {
+        this.buildScriptClassLoader = new GroovyClassLoader(
+                Thread.currentThread().contextClassLoader,
+                new CompilerConfiguration().tap {
+                    scriptBaseClass = BuildScriptBase.name
+                }
+        )
+        classLoaderUrls.each(this.buildScriptClassLoader::addURL)
+    }
+
+    GroovyClassLoader getBuildScriptClassLoader() {
+        this.buildScriptClassLoader
+    }
+
+    Collection<Build> runBuildScript(
+            String scriptName,
+            Map<String, Object> binding,
+            Consumer<BuildScriptBase> configureBuildScript
+    ) {
+        Class<?> scriptClass = this.buildScriptClassLoader.loadClass(
+                ExtensionUtil.stripExtension(scriptName),
+                true,
+                false,
+                false
+        )
+        def scriptObject = scriptClass.getConstructor().newInstance()
+        assert scriptObject instanceof BuildScriptBase
+        scriptObject.setBinding(new Binding(binding))
+        configureBuildScript.accept(scriptObject)
+        runBase(scriptObject)
+    }
+
+}
diff --git a/api/src/main/groovy/com/jessebrault/ssg/buildscript/BuildScripts.groovy b/api/src/main/groovy/com/jessebrault/ssg/buildscript/BuildScripts.groovy
deleted file mode 100644
index 5a217a9..0000000
--- a/api/src/main/groovy/com/jessebrault/ssg/buildscript/BuildScripts.groovy
+++ /dev/null
@@ -1,99 +0,0 @@
-package com.jessebrault.ssg.buildscript
-
-import groovy.transform.stc.ClosureParams
-import groovy.transform.stc.SimpleType
-import org.codehaus.groovy.control.CompilerConfiguration
-
-import java.util.function.Consumer
-
-final class BuildScripts {
-
-    private static Collection<Build> runBase(BuildScriptBase base) {
-        base.run()
-        BuildSpecUtil.getBuilds(base.getBuildSpecs())
-    }
-
-    static Collection<Build> runBuildScript(
-            @DelegatesTo(value = BuildScriptBase, strategy = Closure.DELEGATE_FIRST)
-            @ClosureParams(value = SimpleType, options = 'com.jessebrault.ssg.buildscript.BuildScriptBase')
-            Closure<?> scriptBody
-    ) {
-        def base = new BuildScriptBase() {
-
-            @Override
-            Object run() {
-                scriptBody.delegate = this
-                scriptBody.resolveStrategy = Closure.DELEGATE_FIRST
-                scriptBody.call(this)
-            }
-
-        }
-        runBase(base)
-    }
-
-    static Collection<Build> runBuildScript(
-            String scriptName,
-            GroovyScriptEngine engine,
-            Map<String, Object> binding = [:],
-            Consumer<BuildScriptBase> configureBuildScript = { }
-    ) {
-        engine.config = new CompilerConfiguration().tap {
-            scriptBaseClass = 'com.jessebrault.ssg.buildscript.BuildScriptBase'
-        }
-
-        def base = engine.createScript(scriptName, new Binding(binding))
-        assert base instanceof BuildScriptBase
-        configureBuildScript.accept(base)
-        runBase(base)
-    }
-
-    @Deprecated
-    static Collection<Build> runBuildScript(
-            String scriptName,
-            URL scriptBaseDirUrl,
-            Collection<URL> otherUrls,
-            Map<String, Object> binding,
-            Consumer<BuildScriptBase> configureBuildScript
-    ) {
-        def engine = new GroovyScriptEngine([scriptBaseDirUrl, *otherUrls] as URL[])
-
-        engine.config = new CompilerConfiguration().tap {
-            scriptBaseClass = 'com.jessebrault.ssg.buildscript.BuildScriptBase'
-        }
-
-        def base = engine.createScript(scriptName, new Binding(binding))
-        assert base instanceof BuildScriptBase
-        configureBuildScript.accept(base)
-        runBase(base)
-    }
-
-    @Deprecated
-    static Collection<Build> runBuildScript(
-            String scriptName,
-            URL scriptBaseDirUrl,
-            Collection<URL> otherUrls,
-            Map<String, Object> binding
-    ) {
-        runBuildScript(scriptName, scriptBaseDirUrl, otherUrls, binding) { }
-    }
-
-    @Deprecated
-    static Collection<Build> runBuildScript(
-            String scriptName,
-            URL scriptBaseDirUrl,
-            Collection<URL> otherUrls
-    ) {
-        runBuildScript(scriptName, scriptBaseDirUrl, otherUrls, [:]) { }
-    }
-
-    @Deprecated
-    static Collection<Build> runBuildScript(
-            String scriptName,
-            URL scriptBaseDirUrl
-    ) {
-        runBuildScript(scriptName, scriptBaseDirUrl, [], [:]) { }
-    }
-
-    private BuildScripts() {}
-
-}
diff --git a/api/src/main/groovy/com/jessebrault/ssg/buildscript/DefaultBuildScriptConfiguratorFactory.groovy b/api/src/main/groovy/com/jessebrault/ssg/buildscript/DefaultBuildScriptConfiguratorFactory.groovy
index 4abfea8..23cae26 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/buildscript/DefaultBuildScriptConfiguratorFactory.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/buildscript/DefaultBuildScriptConfiguratorFactory.groovy
@@ -1,5 +1,6 @@
 package com.jessebrault.ssg.buildscript
 
+import com.jessebrault.ssg.html.PageToHtmlSpecProviders
 import com.jessebrault.ssg.html.PageToHtmlTaskFactory
 import com.jessebrault.ssg.html.TextToHtmlSpecProviders
 import com.jessebrault.ssg.html.TextToHtmlTaskFactory
@@ -16,6 +17,7 @@ import groovy.transform.NullCheck
 import groovy.transform.TupleConstructor
 
 import java.util.function.Consumer
+import java.util.function.Supplier
 
 @TupleConstructor(includeFields = true, defaults = false)
 @NullCheck(includeGenerated = true)
@@ -23,8 +25,7 @@ import java.util.function.Consumer
 final class DefaultBuildScriptConfiguratorFactory implements BuildScriptConfiguratorFactory {
 
     private final File baseDir
-    private final File tmpDir
-    private final GroovyScriptEngine engine
+    private final Supplier<ClassLoader> classLoaderSupplier
 
     @Override
     Consumer<BuildScriptBase> get() {
@@ -36,9 +37,9 @@ final class DefaultBuildScriptConfiguratorFactory implements BuildScriptConfigur
 
                 types {
                     textTypes << TextTypes.MARKDOWN
-                    pageTypes << PageTypes.getGsp(['.gsp', '.ssg.gst'], this.tmpDir, this.engine)
-                    templateTypes << TemplateTypes.getGsp(['.gsp', '.ssg.gst'], this.tmpDir, this.engine)
-                    partTypes << PartTypes.getGsp(['.gsp', '.ssg.gst'], this.tmpDir, this.engine)
+                    pageTypes << PageTypes.getGsp(['.gsp', '.ssg.gst'], this.classLoaderSupplier.get())
+                    templateTypes << TemplateTypes.getGsp(['.gsp', '.ssg.gst'], this.classLoaderSupplier.get())
+                    partTypes << PartTypes.getGsp(['.gsp', '.ssg.gst'], this.classLoaderSupplier.get())
                 }
 
                 sources { base, types ->
@@ -50,14 +51,14 @@ final class DefaultBuildScriptConfiguratorFactory implements BuildScriptConfigur
 
                 taskFactories { base, sources ->
                     register('textToHtml', TextToHtmlTaskFactory::new) {
-                        it.specProvider += TextToHtmlSpecProviders.from(sources)
+                        it.specsProvider += TextToHtmlSpecProviders.from(sources)
                         it.allTextsProvider += sources.textsProvider
                         it.allPartsProvider += sources.partsProvider
                         it.allModelsProvider += sources.modelsProvider
                     }
 
                     register('pageToHtml', PageToHtmlTaskFactory::new) {
-                        it.pagesProvider += sources.pagesProvider
+                        it.specsProvider += PageToHtmlSpecProviders.from(sources.pagesProvider)
                         it.allTextsProvider += sources.textsProvider
                         it.allPartsProvider += sources.partsProvider
                         it.allModelsProvider += sources.modelsProvider
diff --git a/api/src/main/groovy/com/jessebrault/ssg/buildscript/SourceProviders.groovy b/api/src/main/groovy/com/jessebrault/ssg/buildscript/SourceProviders.groovy
index b3c3f92..9c85e65 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/buildscript/SourceProviders.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/buildscript/SourceProviders.groovy
@@ -13,8 +13,7 @@ import groovy.transform.EqualsAndHashCode
 import groovy.transform.NullCheck
 import groovy.transform.TupleConstructor
 
-@TupleConstructor(defaults = false)
-@NullCheck(includeGenerated = true)
+@NullCheck
 @EqualsAndHashCode
 final class SourceProviders {
 
@@ -26,22 +25,24 @@ final class SourceProviders {
                 sp0.modelsProvider + sp1.modelsProvider,
                 sp0.pagesProvider + sp1.pagesProvider,
                 sp0.templatesProvider + sp1.templatesProvider,
-                sp0.partsProvider + sp1.partsProvider
+                sp0.partsProvider + sp1.partsProvider,
+                sp0.custom + sp1.custom
         )
     }
 
     static SourceProviders get(Map<String, Object> args) {
         new SourceProviders(
-                args?.textsProvider as CollectionProvider<Text>
+                args.textsProvider as CollectionProvider<Text>
                         ?: CollectionProviders.getEmpty() as CollectionProvider<Text>,
-                args?.modelsProvider as CollectionProvider<Model<Object>>
+                args.modelsProvider as CollectionProvider<Model<Object>>
                         ?: CollectionProviders.getEmpty() as CollectionProvider<Model<Object>>,
-                args?.pagesProvider as CollectionProvider<Page>
+                args.pagesProvider as CollectionProvider<Page>
                         ?: CollectionProviders.getEmpty() as CollectionProvider<Page>,
-                args?.templatesProvider as CollectionProvider<Template>
+                args.templatesProvider as CollectionProvider<Template>
                         ?: CollectionProviders.getEmpty() as CollectionProvider<Template>,
-                args?.partsProvider as CollectionProvider<Part>
-                        ?: CollectionProviders.getEmpty() as CollectionProvider<Part>
+                args.partsProvider as CollectionProvider<Part>
+                        ?: CollectionProviders.getEmpty() as CollectionProvider<Part>,
+                args.custom as Map<String, CollectionProvider<?>> ?: [:]
         )
     }
 
@@ -51,7 +52,8 @@ final class SourceProviders {
                 CollectionProviders.getEmpty(),
                 CollectionProviders.getEmpty(),
                 CollectionProviders.getEmpty(),
-                CollectionProviders.getEmpty()
+                CollectionProviders.getEmpty(),
+                [:]
         )
     }
 
@@ -61,10 +63,40 @@ final class SourceProviders {
     final CollectionProvider<Template> templatesProvider
     final CollectionProvider<Part> partsProvider
 
+    private final Map<String, CollectionProvider<Object>> custom
+
+    SourceProviders(
+            CollectionProvider<Text> textsProvider,
+            CollectionProvider<Model<Object>> modelsProvider,
+            CollectionProvider<Page> pagesProvider,
+            CollectionProvider<Template> templatesProvider,
+            CollectionProvider<Part> partsProvider,
+            Map<String, CollectionProvider<Object>> custom
+    ) {
+        this.textsProvider = textsProvider
+        this.modelsProvider = modelsProvider
+        this.pagesProvider = pagesProvider
+        this.templatesProvider = templatesProvider
+        this.partsProvider = partsProvider
+        this.custom = custom
+    }
+
     SourceProviders plus(SourceProviders other) {
         concat(this, other)
     }
 
+    def <T> CollectionProvider<T> getCustom(String name, Class<T> tClass) {
+        this.custom.get(name) as CollectionProvider<T>
+    }
+
+    void putCustom(String name, CollectionProvider<?> customProvider) {
+        this.custom.put(name, customProvider as CollectionProvider<Object>)
+    }
+
+    Map<String, CollectionProvider<Object>> getAllCustom() {
+        this.custom
+    }
+
     @Override
     String toString() {
         "SourceProviders(textsProvider: ${ this.textsProvider }, modelsProvider: ${ this.modelsProvider }, " +
diff --git a/api/src/main/groovy/com/jessebrault/ssg/buildscript/delegates/SourceProvidersDelegate.groovy b/api/src/main/groovy/com/jessebrault/ssg/buildscript/delegates/SourceProvidersDelegate.groovy
index c4ab368..3764ce9 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/buildscript/delegates/SourceProvidersDelegate.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/buildscript/delegates/SourceProvidersDelegate.groovy
@@ -21,6 +21,8 @@ final class SourceProvidersDelegate {
     private CollectionProvider<Template> templatesProvider = CollectionProviders.getEmpty()
     private CollectionProvider<Part> partsProvider = CollectionProviders.getEmpty()
 
+    private final Map<String, CollectionProvider<Object>> custom = [:]
+
     void texts(CollectionProvider<Text> textsProvider) {
         this.textsProvider += textsProvider
     }
@@ -41,13 +43,18 @@ final class SourceProvidersDelegate {
         this.partsProvider += partsProvider
     }
 
+    void custom(String name, CollectionProvider<?> customProvider) {
+        this.custom.put(name, customProvider as CollectionProvider<Object>)
+    }
+
     SourceProviders getResult() {
         new SourceProviders(
                 this.textsProvider,
                 this.modelsProvider,
                 this.pagesProvider,
                 this.templatesProvider,
-                this.partsProvider
+                this.partsProvider,
+                this.custom
         )
     }
 
diff --git a/api/src/main/groovy/com/jessebrault/ssg/html/PageToHtmlSpec.groovy b/api/src/main/groovy/com/jessebrault/ssg/html/PageToHtmlSpec.groovy
new file mode 100644
index 0000000..869f101
--- /dev/null
+++ b/api/src/main/groovy/com/jessebrault/ssg/html/PageToHtmlSpec.groovy
@@ -0,0 +1,17 @@
+package com.jessebrault.ssg.html
+
+import com.jessebrault.ssg.page.Page
+import com.jessebrault.ssg.task.TaskSpec
+import groovy.transform.EqualsAndHashCode
+import groovy.transform.NullCheck
+import groovy.transform.TupleConstructor
+
+import java.util.function.Function
+
+@TupleConstructor(defaults = false)
+@NullCheck(includeGenerated = true)
+@EqualsAndHashCode
+final class PageToHtmlSpec {
+    final Page page
+    final Function<TaskSpec, String> toRelativeHtmlPath
+}
diff --git a/api/src/main/groovy/com/jessebrault/ssg/html/PageToHtmlSpecProviders.groovy b/api/src/main/groovy/com/jessebrault/ssg/html/PageToHtmlSpecProviders.groovy
new file mode 100644
index 0000000..275a292
--- /dev/null
+++ b/api/src/main/groovy/com/jessebrault/ssg/html/PageToHtmlSpecProviders.groovy
@@ -0,0 +1,32 @@
+package com.jessebrault.ssg.html
+
+import com.jessebrault.ssg.page.Page
+import com.jessebrault.ssg.provider.CollectionProvider
+import com.jessebrault.ssg.provider.CollectionProviders
+import com.jessebrault.ssg.task.TaskSpec
+import com.jessebrault.ssg.util.ExtensionUtil
+
+import java.util.function.Function
+
+final class PageToHtmlSpecProviders {
+
+    static CollectionProvider<PageToHtmlSpec> from(CollectionProvider<Page> pagesProvider) {
+        CollectionProviders.fromCollection(pagesProvider.provide().collect { Page page ->
+            new PageToHtmlSpec(page, { TaskSpec taskSpec ->
+                ExtensionUtil.stripExtension(page.path) + '.html'
+            })
+        })
+    }
+
+    static CollectionProvider<PageToHtmlSpec> from(
+            CollectionProvider<Page> pagesProvider,
+            Function<Page, Function<TaskSpec, String>> toRelativeHtmlPath
+    ) {
+        CollectionProviders.fromCollection(pagesProvider.provide().collect {
+            new PageToHtmlSpec(it, toRelativeHtmlPath.apply(it))
+        })
+    }
+
+    private PageToHtmlSpecProviders() {}
+
+}
diff --git a/api/src/main/groovy/com/jessebrault/ssg/html/PageToHtmlTaskFactory.groovy b/api/src/main/groovy/com/jessebrault/ssg/html/PageToHtmlTaskFactory.groovy
index 3044c1c..6a440f4 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/html/PageToHtmlTaskFactory.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/html/PageToHtmlTaskFactory.groovy
@@ -1,6 +1,6 @@
 package com.jessebrault.ssg.html
 
-import com.jessebrault.ssg.page.Page
+
 import com.jessebrault.ssg.provider.CollectionProvider
 import com.jessebrault.ssg.provider.CollectionProviders
 import com.jessebrault.ssg.task.AbstractRenderTaskFactory
@@ -8,28 +8,27 @@ import com.jessebrault.ssg.task.Task
 import com.jessebrault.ssg.task.TaskSpec
 import com.jessebrault.ssg.util.Result
 
-import static com.jessebrault.ssg.util.ExtensionUtil.stripExtension
 import static java.util.Objects.requireNonNull
 
 final class PageToHtmlTaskFactory extends AbstractRenderTaskFactory {
 
-    CollectionProvider<Page> pagesProvider = CollectionProviders.getEmpty()
+    CollectionProvider<PageToHtmlSpec> specsProvider = CollectionProviders.getEmpty()
 
     @Override
     Result<Collection<Task>> getTasks(TaskSpec taskSpec) {
-        super.checkProviders()
-        requireNonNull(this.pagesProvider)
+        this.checkProviders()
+        requireNonNull(this.specsProvider)
 
         def allTexts = this.allTextsProvider.provide()
         def allModels = this.allModelsProvider.provide()
         def allParts = this.allPartsProvider.provide()
 
-        final Collection<Task> tasks = this.pagesProvider.provide()
+        final Collection<Task> tasks = this.specsProvider.provide()
                 .collect {
                     new PageToHtmlTask(
-                            stripExtension(it.path) + '.html',
+                            it.toRelativeHtmlPath.apply(taskSpec),
                             taskSpec,
-                            it,
+                            it.page,
                             allTexts,
                             allModels,
                             allParts
diff --git a/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlSpec.groovy b/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlSpec.groovy
index 9226fd7..e7215e4 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlSpec.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlSpec.groovy
@@ -1,16 +1,19 @@
 package com.jessebrault.ssg.html
 
+import com.jessebrault.ssg.task.TaskSpec
 import com.jessebrault.ssg.template.Template
 import com.jessebrault.ssg.text.Text
 import groovy.transform.EqualsAndHashCode
 import groovy.transform.NullCheck
 import groovy.transform.TupleConstructor
 
+import java.util.function.Function
+
 @TupleConstructor(defaults = false)
 @NullCheck(includeGenerated = true)
 @EqualsAndHashCode
 final class TextToHtmlSpec {
     final Text text
     final Template template
-    final String path
+    final Function<TaskSpec, String> toRelativeHtmlPath
 }
diff --git a/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlSpecProviders.groovy b/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlSpecProviders.groovy
index 5907a8c..51c2df5 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlSpecProviders.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlSpecProviders.groovy
@@ -3,15 +3,39 @@ package com.jessebrault.ssg.html
 import com.jessebrault.ssg.buildscript.SourceProviders
 import com.jessebrault.ssg.provider.CollectionProvider
 import com.jessebrault.ssg.provider.CollectionProviders
+import com.jessebrault.ssg.task.TaskSpec
+import com.jessebrault.ssg.template.Template
+import com.jessebrault.ssg.text.Text
 import com.jessebrault.ssg.util.ExtensionUtil
 import com.jessebrault.ssg.util.Result
 
+import java.util.function.Function
+
 final class TextToHtmlSpecProviders {
 
     static CollectionProvider<Result<TextToHtmlSpec>> from(SourceProviders sources) {
+        from(sources) { text ->
+            return { TaskSpec taskSpec ->
+                ExtensionUtil.stripExtension(text.path) + '.html'
+            }
+        }
+    }
+
+    static CollectionProvider<Result<TextToHtmlSpec>> from(
+            SourceProviders sources,
+            Function<Text, Function<TaskSpec, String>> toRelativeHtmlPath
+    ) {
+        from(sources.textsProvider, sources.templatesProvider, toRelativeHtmlPath)
+    }
+
+    static CollectionProvider<Result<TextToHtmlSpec>> from(
+            CollectionProvider<Text> textsProvider,
+            CollectionProvider<Template> templatesProvider,
+            Function<Text, Function<TaskSpec, String>> toRelativeHtmlPath
+    ) {
         CollectionProviders.fromSupplier {
-            def templates = sources.templatesProvider.provide()
-            sources.textsProvider.provide().findResults {
+            def templates = templatesProvider.provide()
+            textsProvider.provide().findResults {
                 def frontMatterResult = it.type.frontMatterGetter.get(it)
                 if (frontMatterResult.hasDiagnostics()) {
                     return Result.ofDiagnostics(frontMatterResult.diagnostics) as Result<TextToHtmlSpec>
@@ -22,7 +46,7 @@ final class TextToHtmlSpecProviders {
                     return Result.of(new TextToHtmlSpec(
                             it,
                             template,
-                            ExtensionUtil.stripExtension(it.path) + '.html'
+                            toRelativeHtmlPath.apply(it)
                     ))
                 } else {
                     return null
diff --git a/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlTaskFactory.groovy b/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlTaskFactory.groovy
index 8eaf1f6..8992782 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlTaskFactory.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/html/TextToHtmlTaskFactory.groovy
@@ -12,12 +12,12 @@ import static java.util.Objects.requireNonNull
 
 final class TextToHtmlTaskFactory extends AbstractRenderTaskFactory {
 
-    CollectionProvider<Result<TextToHtmlSpec>> specProvider = CollectionProviders.getEmpty()
+    CollectionProvider<Result<TextToHtmlSpec>> specsProvider = CollectionProviders.getEmpty()
 
     @Override
     Result<Collection<Task>> getTasks(TaskSpec taskSpec) {
         super.checkProviders()
-        requireNonNull(this.specProvider)
+        requireNonNull(this.specsProvider)
 
         def allTexts = this.allTextsProvider.provide()
         def allModels = this.allModelsProvider.provide()
@@ -25,23 +25,22 @@ final class TextToHtmlTaskFactory extends AbstractRenderTaskFactory {
 
         Collection<Diagnostic> diagnostics = []
 
-        final Collection<Task> tasks = this.specProvider.provide()
-                .findResults {
-                    if (it.hasDiagnostics()) {
-                        diagnostics.addAll(it.diagnostics)
-                    } else {
-                        def spec = it.get()
-                        new TextToHtmlTask(
-                                spec.path,
-                                taskSpec,
-                                spec.text,
-                                spec.template,
-                                allTexts,
-                                allModels,
-                                allParts
-                        )
-                    }
-                }
+        final Collection<Task> tasks = this.specsProvider.provide().findResults {
+            if (it.hasDiagnostics()) {
+                diagnostics.addAll(it.diagnostics)
+            } else {
+                def spec = it.get()
+                new TextToHtmlTask(
+                        spec.toRelativeHtmlPath.apply(taskSpec),
+                        taskSpec,
+                        spec.text,
+                        spec.template,
+                        allTexts,
+                        allModels,
+                        allParts
+                )
+            }
+        }
         Result.of(diagnostics, tasks)
     }
 
diff --git a/api/src/main/groovy/com/jessebrault/ssg/page/GspPageRenderer.groovy b/api/src/main/groovy/com/jessebrault/ssg/page/GspPageRenderer.groovy
index 2ca14df..7fd3229 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/page/GspPageRenderer.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/page/GspPageRenderer.groovy
@@ -2,7 +2,6 @@ package com.jessebrault.ssg.page
 
 import com.jessebrault.ssg.render.RenderContext
 import com.jessebrault.ssg.render.StandardGspRenderer
-import com.jessebrault.ssg.util.Diagnostic
 import com.jessebrault.ssg.util.Result
 import groovy.transform.EqualsAndHashCode
 import groovy.transform.NullCheck
@@ -13,8 +12,8 @@ final class GspPageRenderer implements PageRenderer {
 
     private final StandardGspRenderer gspRenderer
 
-    GspPageRenderer(File tmpDir, GroovyScriptEngine engine) {
-        this.gspRenderer = new StandardGspRenderer(tmpDir, engine)
+    GspPageRenderer(ClassLoader parentClassLoader) {
+        this.gspRenderer = new StandardGspRenderer(parentClassLoader)
     }
 
     @Override
diff --git a/api/src/main/groovy/com/jessebrault/ssg/page/PageTypes.groovy b/api/src/main/groovy/com/jessebrault/ssg/page/PageTypes.groovy
index 88688f0..691fb41 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/page/PageTypes.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/page/PageTypes.groovy
@@ -1,9 +1,12 @@
 package com.jessebrault.ssg.page
 
+import groovy.transform.NullCheck
+
+@NullCheck
 final class PageTypes {
 
-    static PageType getGsp(Collection<String> extensions, File tmpDir, GroovyScriptEngine engine) {
-        new PageType(extensions, new GspPageRenderer(tmpDir, engine))
+    static PageType getGsp(Collection<String> extensions, ClassLoader parentClassLoader) {
+        new PageType(extensions, new GspPageRenderer(parentClassLoader))
     }
 
     private PageTypes() {}
diff --git a/api/src/main/groovy/com/jessebrault/ssg/page/PagesProviders.groovy b/api/src/main/groovy/com/jessebrault/ssg/page/PagesProviders.groovy
index 9da7af5..09b983b 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/page/PagesProviders.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/page/PagesProviders.groovy
@@ -6,23 +6,34 @@ import com.jessebrault.ssg.util.ExtensionUtil
 import org.slf4j.Logger
 import org.slf4j.LoggerFactory
 
+import java.util.function.BiPredicate
+import java.util.function.Predicate
+
 final class PagesProviders {
 
     private static final Logger logger = LoggerFactory.getLogger(PagesProviders)
 
     static CollectionProvider<Page> from(File pagesDirectory, Collection<PageType> pageTypes) {
+        from(pagesDirectory, pageTypes) { file, path -> true }
+    }
+
+    static CollectionProvider<Page> from(File pagesDirectory, Collection<PageType> pageTypes, BiPredicate<File, String> filter) {
         CollectionProviders.fromDirectory(pagesDirectory) { file, relativePath ->
-            def extension = ExtensionUtil.getExtension(relativePath)
-            if (extension) {
-                def pageType = pageTypes.find { it.ids.contains(extension) }
-                if (!pageType) {
-                    logger.debug('there is no PageType for file {}; skipping', file)
-                    return null
+            if (filter.test(file, relativePath)) {
+                def extension = ExtensionUtil.getExtension(relativePath)
+                if (extension) {
+                    def pageType = pageTypes.find { it.ids.contains(extension) }
+                    if (!pageType) {
+                        logger.debug('there is no PageType for file {}; skipping', file)
+                        return null
+                    } else {
+                        return new Page(relativePath, pageType, file.getText())
+                    }
                 } else {
-                    return new Page(relativePath, pageType, file.getText())
+                    logger.debug('there is no extension for file {}; skipping', file)
+                    return null
                 }
             } else {
-                logger.debug('there is no extension for file {}; skipping', file)
                 return null
             }
         }
diff --git a/api/src/main/groovy/com/jessebrault/ssg/part/GspPartRenderer.groovy b/api/src/main/groovy/com/jessebrault/ssg/part/GspPartRenderer.groovy
index 235dcde..e134de5 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/part/GspPartRenderer.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/part/GspPartRenderer.groovy
@@ -3,7 +3,6 @@ package com.jessebrault.ssg.part
 import com.jessebrault.ssg.render.RenderContext
 import com.jessebrault.ssg.render.StandardGspRenderer
 import com.jessebrault.ssg.text.Text
-import com.jessebrault.ssg.util.Diagnostic
 import com.jessebrault.ssg.util.Result
 import groovy.transform.EqualsAndHashCode
 import org.jetbrains.annotations.Nullable
@@ -15,8 +14,8 @@ final class GspPartRenderer implements PartRenderer {
 
     private final StandardGspRenderer gspRenderer
 
-    GspPartRenderer(File tmpDir, GroovyScriptEngine engine) {
-        this.gspRenderer = new StandardGspRenderer(tmpDir, engine)
+    GspPartRenderer(ClassLoader parentClassLoader) {
+        this.gspRenderer = new StandardGspRenderer(parentClassLoader)
     }
 
     @Override
diff --git a/api/src/main/groovy/com/jessebrault/ssg/part/PartTypes.groovy b/api/src/main/groovy/com/jessebrault/ssg/part/PartTypes.groovy
index 1602786..949f428 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/part/PartTypes.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/part/PartTypes.groovy
@@ -1,9 +1,12 @@
 package com.jessebrault.ssg.part
 
+import groovy.transform.NullCheck
+
+@NullCheck
 final class PartTypes {
 
-    static PartType getGsp(Collection<String> extensions, File tmpDir, GroovyScriptEngine engine) {
-        new PartType(extensions, new GspPartRenderer(tmpDir, engine))
+    static PartType getGsp(Collection<String> extensions, ClassLoader parentClassLoader) {
+        new PartType(extensions, new GspPartRenderer(parentClassLoader))
     }
 
     private PartTypes() {}
diff --git a/api/src/main/groovy/com/jessebrault/ssg/render/StandardGspRenderer.groovy b/api/src/main/groovy/com/jessebrault/ssg/render/StandardGspRenderer.groovy
index 5450c9f..f9e293e 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/render/StandardGspRenderer.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/render/StandardGspRenderer.groovy
@@ -13,8 +13,8 @@ final class StandardGspRenderer {
 
     private final TemplateCreator templateCreator
 
-    StandardGspRenderer(File tmpDir, GroovyScriptEngine engine) {
-        this.templateCreator = new GroovyTemplateCreator(ExtendedGstParser::new, tmpDir, engine, true)
+    StandardGspRenderer(ClassLoader parentClassLoader) {
+        this.templateCreator = new GroovyTemplateCreator(ExtendedGstParser::new, parentClassLoader, true)
     }
 
     Result<String> render(
diff --git a/api/src/main/groovy/com/jessebrault/ssg/template/GspTemplateRenderer.groovy b/api/src/main/groovy/com/jessebrault/ssg/template/GspTemplateRenderer.groovy
index 2ce11c9..60d436f 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/template/GspTemplateRenderer.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/template/GspTemplateRenderer.groovy
@@ -1,7 +1,6 @@
 package com.jessebrault.ssg.template
 
 import com.jessebrault.ssg.render.StandardGspRenderer
-import com.jessebrault.ssg.util.Diagnostic
 import com.jessebrault.ssg.render.RenderContext
 import com.jessebrault.ssg.util.Result
 import com.jessebrault.ssg.text.Text
@@ -14,8 +13,8 @@ final class GspTemplateRenderer implements TemplateRenderer {
 
     private final StandardGspRenderer gspRenderer
 
-    GspTemplateRenderer(File tmpDir, GroovyScriptEngine engine) {
-        this.gspRenderer = new StandardGspRenderer(tmpDir, engine)
+    GspTemplateRenderer(ClassLoader parentClassLoader) {
+        this.gspRenderer = new StandardGspRenderer(parentClassLoader)
     }
 
     @Override
diff --git a/api/src/main/groovy/com/jessebrault/ssg/template/TemplateTypes.groovy b/api/src/main/groovy/com/jessebrault/ssg/template/TemplateTypes.groovy
index 1f48fec..e4e4e6a 100644
--- a/api/src/main/groovy/com/jessebrault/ssg/template/TemplateTypes.groovy
+++ b/api/src/main/groovy/com/jessebrault/ssg/template/TemplateTypes.groovy
@@ -1,9 +1,12 @@
 package com.jessebrault.ssg.template
 
+import groovy.transform.NullCheck
+
+@NullCheck
 final class TemplateTypes {
 
-    static TemplateType getGsp(Collection<String> extensions, File tmpDir, GroovyScriptEngine engine) {
-        new TemplateType(extensions, new GspTemplateRenderer(tmpDir, engine))
+    static TemplateType getGsp(Collection<String> extensions, ClassLoader parentClassLoader) {
+        new TemplateType(extensions, new GspTemplateRenderer(parentClassLoader))
     }
 
     private TemplateTypes() {}
diff --git a/api/src/test/groovy/com/jessebrault/ssg/BuildScriptBasedStaticSiteGeneratorTests.groovy b/api/src/test/groovy/com/jessebrault/ssg/BuildScriptBasedStaticSiteGeneratorTests.groovy
index 348972d..49e9524 100644
--- a/api/src/test/groovy/com/jessebrault/ssg/BuildScriptBasedStaticSiteGeneratorTests.groovy
+++ b/api/src/test/groovy/com/jessebrault/ssg/BuildScriptBasedStaticSiteGeneratorTests.groovy
@@ -1,14 +1,10 @@
 package com.jessebrault.ssg
 
-import com.jessebrault.ssg.buildscript.BuildScriptBase
-import com.jessebrault.ssg.buildscript.BuildScriptConfiguratorFactory
 import com.jessebrault.ssg.util.ResourceUtil
 import org.junit.jupiter.api.Test
 import org.slf4j.Logger
 import org.slf4j.LoggerFactory
 
-import java.util.function.Consumer
-
 import static com.jessebrault.ssg.util.FileAssertions.assertFileStructureAndContents
 import static org.junit.jupiter.api.Assertions.assertTrue
 
@@ -32,19 +28,17 @@ final class BuildScriptBasedStaticSiteGeneratorTests {
             }
         }
 
-        def tmpDir = File.createTempDir()
-        def engine = new GroovyScriptEngine([sourceDir.toURI().toURL(), tmpDir.toURI().toURL()] as URL[])
-        def ssg = new BuildScriptBasedStaticSiteGenerator(engine, [new BuildScriptConfiguratorFactory() {
+        def ssg = new BuildScriptBasedStaticSiteGenerator([sourceDir.toURI().toURL()], buildScript)
 
-            @Override
-            Consumer<BuildScriptBase> get() {
-                return { }
-            }
-
-        }], buildScript, [sourceDir: sourceDir, tmpDir: tmpDir, engine: engine])
-        assertTrue(ssg.doBuild('test') {
-            it.each { logger.error(it.toString()) }
-        })
+        assertTrue(
+                ssg.doBuild(
+                        'test',
+                        [],
+                        [sourceDir: sourceDir, gclSupplier: ssg::getBuildScriptClassLoader]
+                ) {
+                    it.each { logger.error(it.toString()) }
+                }
+        )
 
         def expectedBase = File.createTempDir()
         new File(expectedBase, 'hello.html').tap {
diff --git a/api/src/test/groovy/com/jessebrault/ssg/buildscript/BuildScriptsTests.groovy b/api/src/test/groovy/com/jessebrault/ssg/buildscript/BuildScriptsTests.groovy
index 0aeb8f6..f6f5804 100644
--- a/api/src/test/groovy/com/jessebrault/ssg/buildscript/BuildScriptsTests.groovy
+++ b/api/src/test/groovy/com/jessebrault/ssg/buildscript/BuildScriptsTests.groovy
@@ -10,189 +10,179 @@ import org.mockito.junit.jupiter.MockitoExtension
 import java.util.function.Consumer
 import java.util.function.Function
 
-import static com.jessebrault.ssg.buildscript.BuildScripts.runBuildScript
+import static BuildScriptRunner.runClosureScript
 import static org.junit.jupiter.api.Assertions.assertEquals
 import static org.mockito.Mockito.verify
 
+@NullCheck
+@ExtendWith(MockitoExtension)
 final class BuildScriptsTests {
 
-    @NullCheck
-    @ExtendWith(MockitoExtension)
-    static final class ScriptFileTests {
-
-        /**
-         * Must be non-static, otherwise Groovy gets confused inside the Closures.
-         *
-         * TODO: use the FileUtil.copyResourceToWriter method
-         */
-        @SuppressWarnings('GrMethodMayBeStatic')
-        private void copyLocalResourceToWriter(String name, Writer target) {
-            BuildScriptsTests.getResourceAsStream(name).withReader {
-                it.transferTo(target)
-            }
+    /**
+     * Must be non-static, otherwise Groovy gets confused inside the Closures.
+     *
+     * TODO: use the FileUtil.copyResourceToWriter method
+     */
+    @SuppressWarnings('GrMethodMayBeStatic')
+    private void copyLocalResourceToWriter(String name, Writer target) {
+        BuildScriptsTests.getResourceAsStream(name).withReader {
+            it.transferTo(target)
         }
-
-        /**
-         * Must be non-static, otherwise Groovy gets confused inside the Closures.
-         */
-        @SuppressWarnings('GrMethodMayBeStatic')
-        private File setupScripts(Collection<String> resourceNames) {
-            def tempDir = File.createTempDir()
-            new FileTreeBuilder(tempDir).tap {
-                resourceNames.each { String resourceName ->
-                    file(resourceName).withWriter {
-                        this.copyLocalResourceToWriter(resourceName, it)
-                    }
-                }
-            }
-            tempDir
-        }
-
-        private static Collection<Build> getBuilds(
-                String scriptName,
-                Collection<URL> urls,
-                Map<String, Object> binding = [:],
-                Consumer<BuildScriptBase> configureBase = { }
-        ) {
-            runBuildScript(scriptName, new GroovyScriptEngine(urls as URL[]), binding, configureBase)
-        }
-
-        @Test
-        void simpleScript() {
-            def baseDir = this.setupScripts(['simple.groovy'])
-            def builds = getBuilds('simple.groovy', [baseDir.toURI().toURL()])
-            assertEquals(1, builds.size())
-            assertEquals('test', builds[0].name)
-        }
-
-        @Test
-        void testImport() {
-            def baseDir = this.setupScripts(['testImport.groovy', 'TestHtmlTask.groovy'])
-            def builds = getBuilds('testImport.groovy', [baseDir.toURI().toURL()])
-            assertEquals(1, builds.size())
-            assertEquals('test', builds[0].name)
-        }
-
-        @Test
-        void buildSrcTest() {
-            def baseDir = File.createTempDir()
-            new FileTreeBuilder(baseDir).tap {
-                file('buildSrcTest.groovy').withWriter {
-                    this.copyLocalResourceToWriter('buildSrcTest.groovy', it)
-                }
-                dir('buildSrc') {
-                    file('AnotherTask.groovy').withWriter {
-                        this.copyLocalResourceToWriter('buildSrc/AnotherTask.groovy', it)
-                    }
-                }
-            }
-            def builds = getBuilds(
-                    'buildSrcTest.groovy',
-                    [
-                            baseDir.toURI().toURL(),
-                            new File(baseDir, 'buildSrc').toURI().toURL()
-                    ]
-            )
-            assertEquals(1, builds.size())
-            assertEquals('test', builds[0].name)
-        }
-
-        @Test
-        void withBinding(@Mock Consumer<String> stringConsumer) {
-            def baseDir = this.setupScripts(['withBinding.groovy'])
-            def engine = new GroovyScriptEngine([baseDir.toURI().toURL()] as URL[])
-            runBuildScript('withBinding.groovy', engine, [stringConsumer: stringConsumer])
-            verify(stringConsumer).accept('test')
-        }
-
     }
 
-    @ExtendWith(MockitoExtension)
-    static final class ClosureScriptTests {
-
-        @Test
-        void simple() {
-            def result = runBuildScript {
-                build(name: 'test') { }
-            }
-            assertEquals(1, result.size())
-            assertEquals('test', result[0].name)
-        }
-
-        @Test
-        void oneBuildOutputDirWithFunction(@Mock Function<Build, OutputDir> mockOutputDirFunction) {
-            def r = runBuildScript {
-                build(name: 'test') {
-                    outputDirFunction = mockOutputDirFunction
+    /**
+     * Must be non-static, otherwise Groovy gets confused inside the Closures.
+     */
+    @SuppressWarnings('GrMethodMayBeStatic')
+    private File setupScripts(Collection<String> resourceNames) {
+        def tempDir = File.createTempDir()
+        new FileTreeBuilder(tempDir).tap {
+            resourceNames.each { String resourceName ->
+                file(resourceName).withWriter {
+                    this.copyLocalResourceToWriter(resourceName, it)
                 }
             }
-            assertEquals(1, r.size())
-            def b0 = r[0]
-            assertEquals(mockOutputDirFunction, b0.outputDirFunction)
         }
+        tempDir
+    }
 
-        @Test
-        void oneBuildOutputDirWithFile() {
-            def f = new File('test')
-            def r = runBuildScript {
-                build(name: 'test') {
-                    outputDir = f
+    private static Collection<Build> getBuilds(
+            String scriptName,
+            Collection<URL> urls,
+            Map<String, Object> binding = [:],
+            Consumer<BuildScriptBase> configureBase = { }
+    ) {
+        new BuildScriptRunner(urls).runBuildScript(scriptName, binding, configureBase)
+    }
+
+    @Test
+    void simpleScript() {
+        def baseDir = this.setupScripts(['simple.groovy'])
+        def builds = getBuilds('simple.groovy', [baseDir.toURI().toURL()])
+        assertEquals(1, builds.size())
+        assertEquals('test', builds[0].name)
+    }
+
+    @Test
+    void testImport() {
+        def baseDir = this.setupScripts(['testImport.groovy', 'TestHtmlTask.groovy'])
+        def builds = getBuilds('testImport.groovy', [baseDir.toURI().toURL()])
+        assertEquals(1, builds.size())
+        assertEquals('test', builds[0].name)
+    }
+
+    @Test
+    void buildSrcTest() {
+        def baseDir = File.createTempDir()
+        new FileTreeBuilder(baseDir).tap {
+            file('buildSrcTest.groovy').withWriter {
+                this.copyLocalResourceToWriter('buildSrcTest.groovy', it)
+            }
+            dir('buildSrc') {
+                file('AnotherTask.groovy').withWriter {
+                    this.copyLocalResourceToWriter('buildSrc/AnotherTask.groovy', it)
                 }
             }
-            assertEquals(1, r.size())
-            def b0 = r[0]
-            assertEquals(f, b0.outputDirFunction.apply(b0) as File)
         }
+        def builds = getBuilds(
+                'buildSrcTest.groovy',
+                [
+                        baseDir.toURI().toURL(),
+                        new File(baseDir, 'buildSrc').toURI().toURL()
+                ]
+        )
+        assertEquals(1, builds.size())
+        assertEquals('test', builds[0].name)
+    }
 
-        @Test
-        void oneBuildOutputDirWithString() {
-            def r = runBuildScript {
-                build(name: 'test') {
-                    outputDir = 'test'
+    @Test
+    void withBinding(@Mock Consumer<String> stringConsumer) {
+        def baseDir = this.setupScripts(['withBinding.groovy'])
+        getBuilds('withBinding.groovy', [baseDir.toURI().toURL()], [stringConsumer: stringConsumer])
+        verify(stringConsumer).accept('test')
+    }
+
+    @Test
+    void simple() {
+        def result = runClosureScript {
+            build(name: 'test') { }
+        }
+        assertEquals(1, result.size())
+        assertEquals('test', result[0].name)
+    }
+
+    @Test
+    void oneBuildOutputDirWithFunction(@Mock Function<Build, OutputDir> mockOutputDirFunction) {
+        def r = runClosureScript {
+            build(name: 'test') {
+                outputDirFunction = mockOutputDirFunction
+            }
+        }
+        assertEquals(1, r.size())
+        def b0 = r[0]
+        assertEquals(mockOutputDirFunction, b0.outputDirFunction)
+    }
+
+    @Test
+    void oneBuildOutputDirWithFile() {
+        def f = new File('test')
+        def r = runClosureScript {
+            build(name: 'test') {
+                outputDir = f
+            }
+        }
+        assertEquals(1, r.size())
+        def b0 = r[0]
+        assertEquals(f, b0.outputDirFunction.apply(b0) as File)
+    }
+
+    @Test
+    void oneBuildOutputDirWithString() {
+        def r = runClosureScript {
+            build(name: 'test') {
+                outputDir = 'test'
+            }
+        }
+        assertEquals(1, r.size())
+        def b0 = r[0]
+        assertEquals('test', b0.outputDirFunction.apply(b0) as String)
+    }
+
+    @Test
+    void oneBuildSiteSpec() {
+        def r = runClosureScript {
+            build(name: 'test') {
+                siteSpec {
+                    name = 'testSite'
+                    baseUrl = 'https://testsite.com'
                 }
             }
-            assertEquals(1, r.size())
-            def b0 = r[0]
-            assertEquals('test', b0.outputDirFunction.apply(b0) as String)
         }
+        assertEquals(1, r.size())
+        def b0 = r[0]
+        assertEquals(new SiteSpec('testSite', 'https://testsite.com'), b0.siteSpec)
+    }
 
-        @Test
-        void oneBuildSiteSpec() {
-            def r = runBuildScript {
-                build(name: 'test') {
-                    siteSpec {
-                        name = 'testSite'
-                        baseUrl = 'https://testsite.com'
-                    }
-                }
-            }
-            assertEquals(1, r.size())
-            def b0 = r[0]
-            assertEquals(new SiteSpec('testSite', 'https://testsite.com'), b0.siteSpec)
-        }
-
-        @Test
-        void oneBuildWithAbstractParent() {
-            def r = runBuildScript {
-                abstractBuild(name: 'parent') {
-                    siteSpec {
-                        name = 'Test Site'
-                        baseUrl = 'https://test.com'
-                    }
-                }
-
-                build(name: 'child', extending: 'parent') {
-                    siteSpec { base ->
-                        baseUrl = base.baseUrl + '/child'
-                    }
+    @Test
+    void oneBuildWithAbstractParent() {
+        def r = runClosureScript {
+            abstractBuild(name: 'parent') {
+                siteSpec {
+                    name = 'Test Site'
+                    baseUrl = 'https://test.com'
                 }
             }
 
-            assertEquals(1, r.size())
-            def b0 = r[0]
-            assertEquals(new SiteSpec('Test Site', 'https://test.com/child'), b0.siteSpec)
+            build(name: 'child', extending: 'parent') {
+                siteSpec { base ->
+                    baseUrl = base.baseUrl + '/child'
+                }
+            }
         }
 
+        assertEquals(1, r.size())
+        def b0 = r[0]
+        assertEquals(new SiteSpec('Test Site', 'https://test.com/child'), b0.siteSpec)
     }
 
 }
diff --git a/api/src/test/groovy/com/jessebrault/ssg/page/GspPageRendererTests.groovy b/api/src/test/groovy/com/jessebrault/ssg/page/GspPageRendererTests.groovy
index 96c8e0a..1642037 100644
--- a/api/src/test/groovy/com/jessebrault/ssg/page/GspPageRendererTests.groovy
+++ b/api/src/test/groovy/com/jessebrault/ssg/page/GspPageRendererTests.groovy
@@ -7,17 +7,14 @@ import com.jessebrault.ssg.util.Result
 final class GspPageRendererTests implements StandardDslConsumerTests {
 
     private static GspPageRenderer getRenderer(
-            ClassLoader classLoader,
-            Collection<URL> urls
+            ClassLoader parentClassLoader = GspPageRendererTests.classLoader
     ) {
-        def tmpDir = File.createTempDir()
-        def engine = new GroovyScriptEngine([tmpDir.toURI().toURL(), *urls] as URL[], classLoader)
-        new GspPageRenderer(tmpDir, engine)
+        new GspPageRenderer(parentClassLoader)
     }
 
     @Override
-    Result<String> render(String scriptlet, RenderContext context, ClassLoader classLoader, Collection<URL> urls) {
-        def renderer = getRenderer(classLoader, urls)
+    Result<String> render(String scriptlet, RenderContext context, ClassLoader classLoader) {
+        def renderer = getRenderer(classLoader)
         renderer.render(
                 new Page('', new PageType([], renderer), scriptlet),
                 context
diff --git a/api/src/test/groovy/com/jessebrault/ssg/part/GspPartRendererTests.groovy b/api/src/test/groovy/com/jessebrault/ssg/part/GspPartRendererTests.groovy
index 253473e..bfae852 100644
--- a/api/src/test/groovy/com/jessebrault/ssg/part/GspPartRendererTests.groovy
+++ b/api/src/test/groovy/com/jessebrault/ssg/part/GspPartRendererTests.groovy
@@ -14,13 +14,8 @@ import static org.junit.jupiter.api.Assertions.assertTrue
 
 final class GspPartRendererTests implements StandardDslConsumerTests {
 
-    private static GspPartRenderer getRenderer(
-            ClassLoader parentClassLoader = GspPartRendererTests.classLoader,
-            Collection<URL> urls = []
-    ) {
-        def tmpDir = File.createTempDir()
-        def engine = new GroovyScriptEngine([tmpDir.toURI().toURL(), *urls] as URL[], parentClassLoader)
-        new GspPartRenderer(tmpDir, engine)
+    private static GspPartRenderer getRenderer(ClassLoader parentClassLoader = GspPartRendererTests.classLoader) {
+        new GspPartRenderer(parentClassLoader)
     }
 
     private static Result<String> doRender(
@@ -28,10 +23,9 @@ final class GspPartRendererTests implements StandardDslConsumerTests {
             RenderContext context,
             Map binding = [:],
             @Nullable Text text = null,
-            ClassLoader classLoader = GspPartRendererTests.classLoader,
-            Collection<URL> urls = []
+            ClassLoader classLoader = GspPartRendererTests.classLoader
     ) {
-        def renderer = getRenderer(classLoader, urls)
+        def renderer = getRenderer(classLoader)
         renderer.render(
                 new Part('', new PartType([], renderer), scriptlet),
                 binding,
@@ -41,8 +35,8 @@ final class GspPartRendererTests implements StandardDslConsumerTests {
     }
 
     @Override
-    Result<String> render(String scriptlet, RenderContext context, ClassLoader classLoader, Collection<URL> urls) {
-        doRender(scriptlet, context, [:], null, classLoader, urls)
+    Result<String> render(String scriptlet, RenderContext context, ClassLoader classLoader) {
+        doRender(scriptlet, context, [:], null, classLoader)
     }
 
     @Test
diff --git a/api/src/test/groovy/com/jessebrault/ssg/template/GspTemplateRendererTests.groovy b/api/src/test/groovy/com/jessebrault/ssg/template/GspTemplateRendererTests.groovy
index 1106e0a..17eabcf 100644
--- a/api/src/test/groovy/com/jessebrault/ssg/template/GspTemplateRendererTests.groovy
+++ b/api/src/test/groovy/com/jessebrault/ssg/template/GspTemplateRendererTests.groovy
@@ -13,29 +13,23 @@ import static org.junit.jupiter.api.Assertions.assertEquals
 
 final class GspTemplateRendererTests implements StandardDslConsumerTests {
 
-    private static TemplateRenderer getRenderer(
-            ClassLoader parentLoader = GspTemplateRendererTests.class.classLoader,
-            Collection<URL> urls = []
-    ) {
-        def tmpDir = File.createTempDir()
-        def engine = new GroovyScriptEngine([tmpDir.toURI().toURL(), *urls] as URL[], parentLoader)
-        new GspTemplateRenderer(tmpDir, engine)
+    private static TemplateRenderer getRenderer(ClassLoader parentClassLoader = GspTemplateRendererTests.classLoader) {
+        new GspTemplateRenderer(parentClassLoader)
     }
 
     private static Result<String> doRender(
             String scriptlet,
             Text text,
             RenderContext context,
-            ClassLoader classLoader,
-            Collection<URL> urls
+            ClassLoader classLoader
     ) {
-        def renderer = getRenderer(classLoader, urls)
+        def renderer = getRenderer(classLoader)
         renderer.render(new Template('', new TemplateType([], renderer), scriptlet), text, context)
     }
 
     @Override
-    Result<String> render(String scriptlet, RenderContext context, ClassLoader classLoader, Collection<URL> urls) {
-        doRender(scriptlet, blankText(), context, classLoader, urls)
+    Result<String> render(String scriptlet, RenderContext context, ClassLoader classLoader) {
+        doRender(scriptlet, blankText(), context, classLoader)
     }
 
     @Test
diff --git a/api/src/test/resources/oneTextAndTemplate.groovy b/api/src/test/resources/oneTextAndTemplate.groovy
index 1d43c5d..0efab64 100644
--- a/api/src/test/resources/oneTextAndTemplate.groovy
+++ b/api/src/test/resources/oneTextAndTemplate.groovy
@@ -9,13 +9,14 @@ import com.jessebrault.ssg.text.TextTypes
 import com.jessebrault.ssg.text.TextsProviders
 import groovy.transform.BaseScript
 
+import java.util.function.Supplier
+
 @BaseScript
 BuildScriptBase b
 
 final class Args {
     File sourceDir
-    File tmpDir
-    GroovyScriptEngine engine
+    Supplier<GroovyClassLoader> gclSupplier
 }
 
 def args = args as Args
@@ -25,7 +26,7 @@ build(name: 'test') {
 
     types {
         textTypes << TextTypes.MARKDOWN
-        templateTypes << TemplateTypes.getGsp(['.gsp'], args.tmpDir, args.engine)
+        templateTypes << TemplateTypes.getGsp(['.gsp'], args.gclSupplier.get())
     }
 
     sources { base, types ->
@@ -35,7 +36,7 @@ build(name: 'test') {
 
     taskFactories { base, sources ->
         register('textToHtml', TextToHtmlTaskFactory::new) {
-            it.specProvider += TextToHtmlSpecProviders.from(sources)
+            it.specsProvider += TextToHtmlSpecProviders.from(sources)
         }
     }
 }
diff --git a/api/src/testFixtures/groovy/com/jessebrault/ssg/dsl/StandardDslConsumerTests.groovy b/api/src/testFixtures/groovy/com/jessebrault/ssg/dsl/StandardDslConsumerTests.groovy
index 25cfccd..74fd21e 100644
--- a/api/src/testFixtures/groovy/com/jessebrault/ssg/dsl/StandardDslConsumerTests.groovy
+++ b/api/src/testFixtures/groovy/com/jessebrault/ssg/dsl/StandardDslConsumerTests.groovy
@@ -33,7 +33,7 @@ import static org.mockito.Mockito.*
 @ExtendWith(MockitoExtension)
 interface StandardDslConsumerTests {
 
-    Result<String> render(String scriptlet, RenderContext context, ClassLoader classLoader, Collection<URL> urls)
+    Result<String> render(String scriptlet, RenderContext context, ClassLoader classLoader)
 
     default void checkResult(String expected, Result<String> result) {
         assertEmptyDiagnostics(result)
@@ -44,21 +44,19 @@ interface StandardDslConsumerTests {
             String expected,
             String scriptlet,
             RenderContext context = new RenderContext(),
-            ClassLoader classLoader = this.class.classLoader,
-            Collection<URL> urls = []
+            ClassLoader classLoader = this.class.classLoader
     ) {
-        this.checkResult(expected, this.render(scriptlet, context, classLoader, urls))
+        this.checkResult(expected, this.render(scriptlet, context, classLoader))
     }
 
     default void doDslAssertionTest(
             String scriptlet,
             RenderContext context = new RenderContext(),
-            ClassLoader classLoader = this.class.classLoader,
-            Collection<URL> urls = []
+            ClassLoader classLoader = this.class.classLoader
     ) {
         Result<String> result = null
         try {
-            result = this.render(scriptlet, context, classLoader, urls)
+            result = this.render(scriptlet, context, classLoader)
         } catch (Throwable e) {
             fail(e)
         }
@@ -279,12 +277,13 @@ interface StandardDslConsumerTests {
                 ['com', 'jessebrault', 'ssg', 'tmp'],
                 greeterText
         )
+        def configuredClassLoader = new GroovyClassLoader(this.class.classLoader)
+        configuredClassLoader.addURL(greeterBaseUrl)
         this.doDslRenderTest(
                 "Hello, World!",
                 "<%@ import com.jessebrault.ssg.tmp.TmpGreeter %><%= new TmpGreeter().greet() %>",
                 new RenderContext(),
-                parentClassLoader,
-                [greeterBaseUrl]
+                configuredClassLoader
         )
     }
 
diff --git a/cli/src/main/groovy/com/jessebrault/ssg/AbstractBuildCommand.groovy b/cli/src/main/groovy/com/jessebrault/ssg/AbstractBuildCommand.groovy
index be23c29..3f2d282 100644
--- a/cli/src/main/groovy/com/jessebrault/ssg/AbstractBuildCommand.groovy
+++ b/cli/src/main/groovy/com/jessebrault/ssg/AbstractBuildCommand.groovy
@@ -1,5 +1,6 @@
 package com.jessebrault.ssg
 
+import com.jessebrault.ssg.buildscript.BuildScriptConfiguratorFactory
 import com.jessebrault.ssg.util.Diagnostic
 import org.apache.logging.log4j.LogManager
 import org.apache.logging.log4j.Logger
@@ -37,23 +38,32 @@ abstract class AbstractBuildCommand extends AbstractSubCommand {
     )
     Collection<String> requestedBuilds = ['default']
 
-    protected StaticSiteGenerator staticSiteGenerator = null
+    protected CliBasedStaticSiteGenerator staticSiteGenerator = null
 
-    protected final Integer doSingleBuild(String requestedBuild, File tmpDir, GroovyScriptEngine engine) {
+    protected final Integer doSingleBuild(
+            String requestedBuild,
+            Collection<BuildScriptConfiguratorFactory> configuratorFactories,
+            Map<String, Object> buildScriptBinding
+    ) {
         logger.traceEntry('requestedBuild: {}', requestedBuild)
 
         if (this.staticSiteGenerator == null) {
             this.staticSiteGenerator = new CliBasedStaticSiteGenerator(
-                    new File('.'),
                     this.buildScript,
-                    tmpDir,
-                    engine,
-                    this.scriptArgs
+                    [
+                            this.buildScript.parentFile.toURI().toURL(),
+                            *this.buildSrcDirs.collect { it.toURI().toURL() }
+                    ]
             )
         }
 
         final Collection<Diagnostic> diagnostics = []
-        if (!this.staticSiteGenerator.doBuild(requestedBuild, diagnostics.&addAll)) {
+        if (!this.staticSiteGenerator.doBuild(
+                requestedBuild,
+                configuratorFactories,
+                buildScriptBinding,
+                diagnostics.&addAll
+        )) {
             diagnostics.each { logger.warn(it) }
             logger.traceExit(1)
         } else {
diff --git a/cli/src/main/groovy/com/jessebrault/ssg/CliBasedStaticSiteGenerator.groovy b/cli/src/main/groovy/com/jessebrault/ssg/CliBasedStaticSiteGenerator.groovy
index da071e8..a0f0e6f 100644
--- a/cli/src/main/groovy/com/jessebrault/ssg/CliBasedStaticSiteGenerator.groovy
+++ b/cli/src/main/groovy/com/jessebrault/ssg/CliBasedStaticSiteGenerator.groovy
@@ -1,6 +1,6 @@
 package com.jessebrault.ssg
 
-import com.jessebrault.ssg.buildscript.DefaultBuildScriptConfiguratorFactory
+import com.jessebrault.ssg.buildscript.BuildScriptConfiguratorFactory
 import com.jessebrault.ssg.util.Diagnostic
 import groovy.transform.PackageScope
 
@@ -9,40 +9,43 @@ import java.util.function.Consumer
 @PackageScope
 final class CliBasedStaticSiteGenerator implements StaticSiteGenerator {
 
-    private final File baseDir
     private final File buildScript
-    private final File tmpDir
-    private final Map<String, String> scriptArgs
-    private final GroovyScriptEngine engine
+    private final Collection<URL> buildScriptClassLoaderUrls
 
-    private StaticSiteGenerator staticSiteGenerator
+    private BuildScriptBasedStaticSiteGenerator delegate
 
+    /**
+     * @param buildScript The buildScript File.
+     * @param buildScriptClassLoaderUrls all the necessary urls to needed to run the given buildScript.
+     *          Likely includes the parent directory of the buildScript, as well as buildSrc dir(s).
+     */
     CliBasedStaticSiteGenerator(
-            File baseDir,
             File buildScript,
-            File tmpDir,
-            GroovyScriptEngine engine,
-            Map<String, String> scriptArgs
+            Collection<URL> buildScriptClassLoaderUrls
     ) {
-        this.baseDir = baseDir
         this.buildScript = buildScript
-        this.tmpDir = tmpDir
-        this.scriptArgs = scriptArgs
-        this.engine = engine
+        this.buildScriptClassLoaderUrls = buildScriptClassLoaderUrls
     }
 
     @Override
-    boolean doBuild(String buildName, Consumer<Collection<Diagnostic>> diagnosticsConsumer) {
-        if (this.staticSiteGenerator == null) {
-            this.staticSiteGenerator = new BuildScriptBasedStaticSiteGenerator(
-                    this.engine,
-                    [new DefaultBuildScriptConfiguratorFactory(this.baseDir, this.tmpDir, this.engine)],
-                    this.buildScript,
-                    this.scriptArgs
+    boolean doBuild(
+            String buildName,
+            Collection<BuildScriptConfiguratorFactory> configuratorFactories,
+            Map<String, Object> buildScriptArgs,
+            Consumer<Collection<Diagnostic>> diagnosticsConsumer
+    ) {
+        if (this.delegate == null) {
+            this.delegate = new BuildScriptBasedStaticSiteGenerator(
+                    this.buildScriptClassLoaderUrls,
+                    this.buildScript
             )
         }
 
-        this.staticSiteGenerator.doBuild(buildName, diagnosticsConsumer)
+        this.delegate.doBuild(buildName, configuratorFactories, buildScriptArgs, diagnosticsConsumer)
+    }
+
+    GroovyClassLoader getBuildScriptClassLoader() {
+        this.delegate.buildScriptClassLoader
     }
 
 }
diff --git a/cli/src/main/groovy/com/jessebrault/ssg/SsgBuild.groovy b/cli/src/main/groovy/com/jessebrault/ssg/SsgBuild.groovy
index 7ff26b2..bc1f4ba 100644
--- a/cli/src/main/groovy/com/jessebrault/ssg/SsgBuild.groovy
+++ b/cli/src/main/groovy/com/jessebrault/ssg/SsgBuild.groovy
@@ -1,5 +1,6 @@
 package com.jessebrault.ssg
 
+import com.jessebrault.ssg.buildscript.DefaultBuildScriptConfiguratorFactory
 import org.apache.logging.log4j.LogManager
 import org.apache.logging.log4j.Logger
 import picocli.CommandLine
@@ -17,13 +18,15 @@ final class SsgBuild extends AbstractBuildCommand {
     protected Integer doSubCommand() {
         logger.traceEntry()
         def result = 0
-        def tmpDir = File.createTempDir()
-        def urls = [tmpDir, *this.buildSrcDirs, new File('.')].collect {
-            it.toURI().toURL()
-        } as URL[]
-        def engine = new GroovyScriptEngine(urls)
         this.requestedBuilds.each {
-            def buildResult = this.doSingleBuild(it, tmpDir, engine)
+            def buildResult = this.doSingleBuild(
+                    it,
+                    [new DefaultBuildScriptConfiguratorFactory(
+                            new File('.'),
+                            this.staticSiteGenerator::getBuildScriptClassLoader
+                    )],
+                    this.scriptArgs
+            )
             if (buildResult == 1) {
                 result = 1
             }
diff --git a/cli/src/test/groovy/com/jessebrault/ssg/CliBasedStaticSiteGeneratorTests.groovy b/cli/src/test/groovy/com/jessebrault/ssg/CliBasedStaticSiteGeneratorTests.groovy
index 861df05..5308839 100644
--- a/cli/src/test/groovy/com/jessebrault/ssg/CliBasedStaticSiteGeneratorTests.groovy
+++ b/cli/src/test/groovy/com/jessebrault/ssg/CliBasedStaticSiteGeneratorTests.groovy
@@ -1,5 +1,6 @@
 package com.jessebrault.ssg
 
+import com.jessebrault.ssg.buildscript.DefaultBuildScriptConfiguratorFactory
 import com.jessebrault.ssg.util.Diagnostic
 import com.jessebrault.ssg.util.ResourceUtil
 import org.junit.jupiter.api.Test
@@ -14,20 +15,17 @@ final class CliBasedStaticSiteGeneratorTests {
         def baseDir = File.createTempDir()
         SsgInit.init(baseDir, true)
 
-        def tmpDir = File.createTempDir()
-        def engine = new GroovyScriptEngine([
-                new File(baseDir, 'buildSrc').toURI().toURL(),
-                tmpDir.toURI().toURL()
-        ] as URL[])
-        def ssg = new CliBasedStaticSiteGenerator(
-                baseDir,
-                new File(baseDir, 'ssgBuilds.groovy'),
-                tmpDir,
-                engine,
-                [:]
-        )
+        def groovyClassLoader = new GroovyClassLoader()
+        [baseDir.toURI().toURL(), new File(baseDir, 'buildSrc').toURI().toURL()]
+                .each(groovyClassLoader::addURL)
+
+        def ssg = new CliBasedStaticSiteGenerator(new File(baseDir, 'ssgBuilds.groovy'), [])
+        def configuratorFactories = [
+                new DefaultBuildScriptConfiguratorFactory(baseDir, ssg::getBuildScriptClassLoader)
+        ]
+
         def diagnostics = [] as Collection<Diagnostic>
-        assertTrue(ssg.doBuild('production', diagnostics.&addAll), {
+        assertTrue(ssg.doBuild('production', configuratorFactories, [:], diagnostics.&addAll), {
             diagnostics.inject('') { acc, diagnostic ->
                 acc + '\n' + diagnostic.message
             }