diff --git a/crates/codegen/src/top_level.rs b/crates/codegen/src/top_level.rs
index a9ef282..94073c5 100644
--- a/crates/codegen/src/top_level.rs
+++ b/crates/codegen/src/top_level.rs
@@ -88,8 +88,11 @@ impl GenRust for FunctionDecl {
             param.gen_rust(ctx, cg);
         }
 
-        cg.add(") -> ");
-        cg.add(&self.return_type.get_rust());
+        cg.add(") ");
+        if let Some(return_type) = &self.return_type {
+            cg.add("-> ");
+            cg.add(&return_type.get_rust());
+        }
 
         if let Some(body) = &self.body {
             cg.add(" ");
@@ -254,7 +257,7 @@ impl GenRust for (&Vec<Spanned<FieldDeclStmt>>, &Spanned<ClassConstructor>) {
                 name: Identifier(String::from("constructor")),
                 generics: self.1.item.generics.clone(),
                 params: ParamList(constructor_params),
-                return_type: TypeExpr::Tuple(Vec::new()),
+                return_type: Some(TypeExpr::Tuple(Vec::new())),
                 body: Some(self.1.item.body.clone()),
             },
         }
diff --git a/crates/parser/src/ast/top_level.rs b/crates/parser/src/ast/top_level.rs
index f87d011..dd29e9b 100644
--- a/crates/parser/src/ast/top_level.rs
+++ b/crates/parser/src/ast/top_level.rs
@@ -97,7 +97,7 @@ pub struct FunctionDecl {
     pub name: Identifier,
     pub generics: GenericsDecl,
     pub params: ParamList,
-    pub return_type: TypeExpr,
+    pub return_type: Option<TypeExpr>,
     pub body: Option<Block>,
 }
 
diff --git a/crates/parser/src/grammar.pest b/crates/parser/src/grammar.pest
index 97e1613..07f4b7b 100644
--- a/crates/parser/src/grammar.pest
+++ b/crates/parser/src/grammar.pest
@@ -192,7 +192,7 @@ attributes = {
 // DECLARATION HELPERS
 // ======================================================
 var_decl = {
-    "let" ~ WHITESPACE ~ pattern ~ type_expr?
+    "let" ~ pattern ~ type_expr?
 }
 
 field = {
@@ -323,7 +323,7 @@ trait_decl = {
 // ======================================================
 
 function_decl = {
-    visibility? ~ type_expr ~ identifier ~ generics_decl? ~ "(" ~ method_args ~ ")" ~ (block | semicolon)
+    visibility? ~ "fn" ~ identifier ~ generics_decl? ~ "(" ~ method_args ~ ")" ~ type_expr? ~ (block | semicolon)
 }
 
 // ======================================================
diff --git a/crates/parser/src/parser/items/function.rs b/crates/parser/src/parser/items/function.rs
index d44d00d..7dbd50c 100644
--- a/crates/parser/src/parser/items/function.rs
+++ b/crates/parser/src/parser/items/function.rs
@@ -13,7 +13,6 @@ impl<'a> TryFrom<pest::iterators::Pair<'a, Rule>> for FunctionDecl {
         ast_ensure!(pair, Rule::function_decl => {
         let mut inner = pair.into_inner();
             let visibility = Visibility::try_from(&mut inner);
-            let return_type = TypeExpr::try_from(inner.next().unwrap());
             let name = Identifier::try_from(inner.next().unwrap());
 
             let generics = consume_rule(&mut inner, Rule::generics_decl)
@@ -51,6 +50,10 @@ impl<'a> TryFrom<pest::iterators::Pair<'a, Rule>> for FunctionDecl {
                 })
                 .unwrap_or_else(|| Ok(ParamList(self_param.into_iter().collect())));
 
+            let return_type = consume_rule(&mut inner, Rule::type_expr)
+                .map(TypeExpr::try_from)
+                .transpose();
+
             let body = inner.next().map(Block::try_from).transpose();
 
             ast_expr!(Self {
diff --git a/mist-test/src/main.mist b/mist-test/src/main.mist
index 0e319b9..6ea27b3 100644
--- a/mist-test/src/main.mist
+++ b/mist-test/src/main.mist
@@ -1,9 +1,9 @@
-void main() {}
+fn main() {}
 
 struct MyStruct<'a> {
     name *'a String
 }
 
-i32 add(a i32, b i32) {
+fn add(a i32, b i32) i32 {
     a + b
 }