diff --git a/dmc-lib/src/asm/mod.rs b/dmc-lib/src/asm/mod.rs
index 996d136..b3359bb 100644
--- a/dmc-lib/src/asm/mod.rs
+++ b/dmc-lib/src/asm/mod.rs
@@ -31,7 +31,7 @@ mod smoke_tests {
     fn multiple_statements() {
         let asm_functions = assemble(
             "
-            extern fn println()
+            extern fn println() -> Void
             fn main()
                 let x = 42
                 println(x)
diff --git a/dmc-lib/src/ast/expression_statement.rs b/dmc-lib/src/ast/expression_statement.rs
index 473cd0c..4474c24 100644
--- a/dmc-lib/src/ast/expression_statement.rs
+++ b/dmc-lib/src/ast/expression_statement.rs
@@ -3,8 +3,11 @@ use crate::ast::assemble_context::AssembleContext;
 use crate::ast::expression::Expression;
 use crate::constants_table::ConstantsTable;
 use crate::diagnostic::Diagnostic;
+use crate::symbol::FunctionSymbol;
 use crate::symbol_table::SymbolTable;
 use crate::type_info::TypeInfo;
+use std::cell::RefCell;
+use std::rc::Rc;
 
 pub struct ExpressionStatement {
     expression: Box<Expression>,
@@ -38,6 +41,7 @@ impl ExpressionStatement {
         context: &mut AssembleContext,
         symbol_table: &SymbolTable,
         constants_table: &mut ConstantsTable,
+        outer_function_symbol: &Rc<RefCell<FunctionSymbol>>,
         is_last: bool,
     ) {
         match self.expression.as_ref() {
@@ -57,7 +61,15 @@ impl ExpressionStatement {
                 }
             }
             Expression::Additive(additive) => {
-                additive.assemble(context, symbol_table, constants_table);
+                let result_register = additive.assemble(context, symbol_table, constants_table);
+                if is_last
+                    && !matches!(outer_function_symbol.borrow().return_type(), TypeInfo::Void)
+                {
+                    // set return value
+                    context.instruction(AsmInstruction::SetReturnValue(SetReturnValue::new(
+                        result_register,
+                    )));
+                }
             }
             _ => unreachable!(),
         }
diff --git a/dmc-lib/src/ast/function.rs b/dmc-lib/src/ast/function.rs
index e7df7f4..61cc40e 100644
--- a/dmc-lib/src/ast/function.rs
+++ b/dmc-lib/src/ast/function.rs
@@ -9,7 +9,9 @@ use crate::source_range::SourceRange;
 use crate::symbol::FunctionSymbol;
 use crate::symbol_table::{SymbolInsertError, SymbolTable};
 use crate::type_info::TypeInfo;
+use std::cell::RefCell;
 use std::ops::Neg;
+use std::rc::Rc;
 
 pub struct Function {
     declared_name: String,
@@ -17,6 +19,7 @@ pub struct Function {
     parameters: Vec<Parameter>,
     return_type: Option<TypeUse>,
     statements: Vec<Statement>,
+    function_symbol: Option<Rc<RefCell<FunctionSymbol>>>,
 }
 
 impl Function {
@@ -33,6 +36,7 @@ impl Function {
             parameters,
             return_type,
             statements,
+            function_symbol: None,
         }
     }
 
@@ -77,6 +81,9 @@ impl Function {
             }
         };
 
+        // save function symbol for later
+        self.function_symbol = Some(function_symbol.clone());
+
         // handle parameters
         symbol_table.push_scope(&format!("parameter_scope({})", self.declared_name));
         let mut parameter_symbols = vec![];
@@ -159,9 +166,19 @@ impl Function {
     ) {
         context.new_function(&self.declared_name, &self.declared_name_source_range);
         context.new_block(&format!("{}_enter", self.declared_name));
+        let function_symbol = self
+            .function_symbol
+            .as_ref()
+            .expect("function_symbol not initialized; did you type check yet?");
         for (i, statement) in self.statements.iter().enumerate() {
             let is_last = i == self.statements.len() - 1;
-            statement.assemble(context, symbol_table, constants_table, is_last);
+            statement.assemble(
+                context,
+                symbol_table,
+                constants_table,
+                function_symbol,
+                is_last,
+            );
         }
         // return
         context.instruction(AsmInstruction::Return(Return::new(self.parameters.len())));
diff --git a/dmc-lib/src/ast/let_statement.rs b/dmc-lib/src/ast/let_statement.rs
index 4cccf68..f9a6ad9 100644
--- a/dmc-lib/src/ast/let_statement.rs
+++ b/dmc-lib/src/ast/let_statement.rs
@@ -43,10 +43,8 @@ impl LetStatement {
     pub fn gather_declared_names(&mut self, symbol_table: &mut SymbolTable) -> Vec<Diagnostic> {
         let mut diagnostics = vec![];
         self.initializer_mut().gather_declared_names(symbol_table);
-        let insert_result = symbol_table.insert_variable_symbol(VariableSymbol::new(
-            self.declared_name(),
-            self.initializer().type_info().clone(),
-        ));
+        let insert_result =
+            symbol_table.insert_variable_symbol(VariableSymbol::new(self.declared_name()));
         if let Err(symbol_insert_error) = insert_result {
             match symbol_insert_error {
                 SymbolInsertError::AlreadyDeclared(already_declared) => {
@@ -70,9 +68,17 @@ impl LetStatement {
     }
 
     pub fn type_check(&mut self, symbol_table: &SymbolTable) -> Vec<Diagnostic> {
-        let mut diagnostics = vec![];
-        diagnostics.append(&mut self.initializer.type_check(symbol_table));
-        diagnostics
+        let initializer_diagnostics = self.initializer.type_check(symbol_table);
+        if !initializer_diagnostics.is_empty() {
+            return initializer_diagnostics;
+        }
+        let initializer_type_info = self.initializer.type_info();
+        let variable_symbol =
+            symbol_table.get_variable_symbol(self.scope_id.unwrap(), &self.declared_name);
+        variable_symbol
+            .borrow_mut()
+            .set_type_info(initializer_type_info);
+        vec![]
     }
 
     pub fn assemble(
diff --git a/dmc-lib/src/ast/statement.rs b/dmc-lib/src/ast/statement.rs
index 86d37f3..807bf36 100644
--- a/dmc-lib/src/ast/statement.rs
+++ b/dmc-lib/src/ast/statement.rs
@@ -3,7 +3,10 @@ use crate::ast::expression_statement::ExpressionStatement;
 use crate::ast::let_statement::LetStatement;
 use crate::constants_table::ConstantsTable;
 use crate::diagnostic::Diagnostic;
+use crate::symbol::FunctionSymbol;
 use crate::symbol_table::SymbolTable;
+use std::cell::RefCell;
+use std::rc::Rc;
 
 pub enum Statement {
     Let(LetStatement),
@@ -43,6 +46,7 @@ impl Statement {
         context: &mut AssembleContext,
         symbol_table: &SymbolTable,
         constants_table: &mut ConstantsTable,
+        outer_function_symbol: &Rc<RefCell<FunctionSymbol>>,
         is_last: bool,
     ) {
         match self {
@@ -50,7 +54,13 @@ impl Statement {
                 let_statement.assemble(context, symbol_table, constants_table);
             }
             Statement::Expression(expression_statement) => {
-                expression_statement.assemble(context, symbol_table, constants_table, is_last);
+                expression_statement.assemble(
+                    context,
+                    symbol_table,
+                    constants_table,
+                    outer_function_symbol,
+                    is_last,
+                );
             }
         }
     }
diff --git a/dmc-lib/src/symbol.rs b/dmc-lib/src/symbol.rs
index 1f990ed..5f87e31 100644
--- a/dmc-lib/src/symbol.rs
+++ b/dmc-lib/src/symbol.rs
@@ -82,15 +82,15 @@ impl ParameterSymbol {
 
 pub struct VariableSymbol {
     name: Rc<str>,
-    type_info: TypeInfo,
+    type_info: Option<TypeInfo>,
     register: Option<usize>,
 }
 
 impl VariableSymbol {
-    pub fn new(name: &str, type_info: TypeInfo) -> Self {
+    pub fn new(name: &str) -> Self {
         Self {
             name: name.into(),
-            type_info,
+            type_info: None,
             register: None,
         }
     }
@@ -103,8 +103,14 @@ impl VariableSymbol {
         self.name.clone()
     }
 
+    pub fn set_type_info(&mut self, type_info: TypeInfo) {
+        self.type_info = Some(type_info);
+    }
+
     pub fn type_info(&self) -> &TypeInfo {
-        &self.type_info
+        self.type_info
+            .as_ref()
+            .expect("TypeInfo not initialized. Did you type check?")
     }
 
     pub fn set_register(&mut self, register: usize) {
diff --git a/dvm-lib/src/vm/mod.rs b/dvm-lib/src/vm/mod.rs
index a1cd40c..c3cc771 100644
--- a/dvm-lib/src/vm/mod.rs
+++ b/dvm-lib/src/vm/mod.rs
@@ -180,6 +180,11 @@ pub fn call<'a>(
     function_name: &str,
     arguments: Vec<Value>,
 ) -> Option<Value> {
+    // check if DVM_DEBUG is enabled
+    let debug = std::env::var("DVM_DEBUG")
+        .map(|s| s.eq("1"))
+        .unwrap_or(false);
+
     let function = context
         .functions
         .get(function_name)
@@ -203,7 +208,9 @@ pub fn call<'a>(
         && call_stack.top().ip() < call_stack.top().instructions().len()
     {
         let instruction = &call_stack.top().instructions()[call_stack.top().ip()];
-        // println!("{}", instruction);
+        if debug {
+            println!("{}", instruction);
+        }
 
         match instruction {
             /* Move instructions */
@@ -361,13 +368,14 @@ pub fn call<'a>(
             }
 
             Instruction::Return(caller_pop_count) => {
-                call_stack.pop(); // pop this frame
+                let mut callee = call_stack.pop(); // pop this frame
                 let maybe_caller = call_stack.maybe_top_mut();
                 if let Some(caller) = maybe_caller {
                     for _ in 0..*caller_pop_count {
                         caller.stack_mut().pop();
                     }
-                    if let Some(return_value) = caller.take_return_value() {
+                    if let Some(return_value) = callee.take_return_value() {
+                        // n.b. callee
                         caller.stack_mut().push(return_value);
                     }
                 }
@@ -375,11 +383,13 @@ pub fn call<'a>(
             }
         }
 
-        // if let Some(top) = call_stack.maybe_top() {
-        //     println!("  stack: {:?}", top.stack());
-        //     println!("  registers: {:?}", registers);
-        //     println!("  rv: {:?}", top.return_value());
-        // }
+        if debug {
+            if let Some(top) = call_stack.maybe_top() {
+                println!("  stack: {:?}", top.stack());
+                println!("  registers: {:?}", registers);
+                println!("  rv: {:?}", top.return_value());
+            }
+        }
     }
     None // todo: returning results from main functions
 }
diff --git a/examples/call.dm b/examples/call.dm
index 5228904..0aa5ea2 100644
--- a/examples/call.dm
+++ b/examples/call.dm
@@ -1,12 +1,11 @@
 extern fn println(message: Any) -> Void
 
-fn add(a: Int, b: Int) -> Void
-    println(a + b)
+fn add(a: Int, b: Int) -> Int
+    a + b
 end
 
 fn main()
-    let x = 1 + 2 + 3
-    add(x, 1)
-    add(x, 2)
-    add(21, 21)
+    let y = add(1, 2)
+    println(y)
+    println(add(3, add(4, 5)))
 end
\ No newline at end of file