diff --git a/src/ast/build.rs b/src/ast/build.rs
index c3847a3..569f4a8 100644
--- a/src/ast/build.rs
+++ b/src/ast/build.rs
@@ -1,6 +1,7 @@
 use crate::ast::*;
 use crate::parser::Rule;
 use pest::iterators::{Pair, Pairs};
+use std::str::FromStr;
 
 fn expect_and_use<T>(
     file_id: usize,
@@ -1227,7 +1228,27 @@ fn build_literal(file_id: usize, literal_pair: Pair<Rule>) -> Literal {
 }
 
 fn build_number_literal(file_id: usize, pair: Pair<Rule>) -> Literal {
-    todo!()
+    let inner_pair = pair.into_inner().next().unwrap();
+    match inner_pair.as_rule() {
+        Rule::DoubleLiteral => build_double_literal(file_id, inner_pair),
+        Rule::LongLiteral => build_long_literal(file_id, inner_pair),
+        Rule::IntLiteral => build_int_literal(file_id, inner_pair),
+        _ => unreachable!(),
+    }
+}
+
+fn build_double_literal(file_id: usize, inner_pair: Pair<Rule>) -> Literal {
+    Literal::Double(f64::from_str(&inner_pair.as_str()).unwrap())
+}
+
+fn build_long_literal(file_id: usize, inner_pair: Pair<Rule>) -> Literal {
+    let as_string = inner_pair.as_str();
+    let without_el = &as_string[0..(as_string.len() - 1)];
+    Literal::Long(i64::from_str(without_el).unwrap())
+}
+
+fn build_int_literal(file_id: usize, inner_pair: Pair<Rule>) -> Literal {
+    Literal::Integer(i32::from_str(&inner_pair.as_str()).unwrap())
 }
 
 fn build_string_literal(file_id: usize, pair: Pair<Rule>) -> Literal {
@@ -1265,15 +1286,16 @@ fn build_backtick_string(file_id: usize, pair: Pair<Rule>) -> Literal {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::ast::pretty_print::PrettyPrint;
     use crate::parser::DeimosParser;
     use indoc::indoc;
 
-    fn assert_builds(src: &str) {
+    fn assert_builds(src: &str) -> CompilationUnit {
         let parse_result = DeimosParser::parse(Rule::CompilationUnit, src);
         if let Err(e) = parse_result {
             panic!("Parsing failed.\n{}", e)
         } else {
-            build_ast(0, parse_result.unwrap().next().unwrap());
+            build_ast(0, parse_result.unwrap().next().unwrap())
         }
     }
 
@@ -1283,15 +1305,30 @@ mod tests {
         fn main() {
             let x = foo[a];
         }
-        "})
+        "});
     }
 
     #[test]
     fn object_index_and_call() {
-        assert_builds(indoc! {"\
+        assert_builds(indoc! {"
         fn main() {
             a[b]().c()
         }
-        "})
+        "});
+    }
+
+    #[test]
+    fn int_literal() {
+        assert_builds("fn main() { 0 }");
+    }
+
+    #[test]
+    fn long_literal() {
+        assert_builds("fn main() { 1L }");
+    }
+
+    #[test]
+    fn double_literal() {
+        assert_builds("fn main() { 1.0 }");
     }
 }