diff --git a/src/ast.ts b/src/ast.ts
index d9172d3..e5e3dc8 100644
--- a/src/ast.ts
+++ b/src/ast.ts
@@ -14,7 +14,8 @@ interface ASTResolveResults {
 
 abstract class ASTNode {
     public abstract resolve(
-        results: ASTResolveResults
+        results: ASTResolveResults,
+        returnType: DataType
     ): void;
 
     public abstract marker(): Token;
diff --git a/src/ast_expr.ts b/src/ast_expr.ts
index 62c4e13..8c2c72c 100644
--- a/src/ast_expr.ts
+++ b/src/ast_expr.ts
@@ -46,7 +46,8 @@ class ExprASTBool implements ExpressionAST {
     }
 
     public resolve(
-        results: ASTResolveResults
+        results: ASTResolveResults,
+        returnType: DataType
     ): void { }
 
     public marker(): Token {
@@ -83,7 +84,8 @@ class ExprASTString implements ExpressionAST {
     }
 
     public resolve(
-        results: ASTResolveResults
+        results: ASTResolveResults,
+        returnType: DataType
     ): void { }
 
     public marker(): Token {
@@ -143,7 +145,10 @@ class ExprASTInt implements ExpressionAST {
             );
     }
 
-    public resolve(results: ASTResolveResults): void {
+    public resolve(
+        results: ASTResolveResults,
+        returnType: DataType
+    ): void {
         switch(this.bit) {
             case 4:
                 this.minMaxFlow(
@@ -223,7 +228,10 @@ class ExprASTFloat implements ExpressionAST {
         return LLVMDataType.getFloatDataType(this.bit);
     }
 
-    public resolve(): void { }
+    public resolve(
+        results: ASTResolveResults,
+        returnType: DataType
+    ): void { }
 
     public marker(): Token {
         return this.mark;
@@ -295,7 +303,10 @@ class ExprASTUnary implements ExpressionAST {
         return this.expr.type();
     }
 
-    public resolve(results: ASTResolveResults): void {
+    public resolve(
+        results: ASTResolveResults,
+        returnType: DataType
+    ): void {
         const dataType: DataType = this.expr.type();
         const mrk: Token = this.marker();
 
@@ -416,7 +427,10 @@ class ExprASTEquality implements ExpressionAST {
         return DataType.BOOL;
     }
 
-    public resolve(results: ASTResolveResults): void {
+    public resolve(
+        results: ASTResolveResults,
+        returnType: DataType
+    ): void {
         const leftType: DataType =
             this.left.type();
         const rightType: DataType =
@@ -467,8 +481,8 @@ class ExprASTEquality implements ExpressionAST {
                 ' is not allowed.'
             );
 
-        this.left.resolve(results);
-        this.right.resolve(results);
+        this.left.resolve(results, returnType);
+        this.right.resolve(results, returnType);
     }
 
     public marker(): Token {
@@ -556,7 +570,8 @@ class ExprASTAndOr implements ExpressionAST {
     }
 
     public resolve(
-        results: ASTResolveResults
+        results: ASTResolveResults,
+        returnType: DataType
     ): void {
         const leftType: DataType =
             this.left.type();
@@ -600,9 +615,8 @@ class ExprASTAndOr implements ExpressionAST {
                 );
         }
 
-
-        this.left.resolve(results);
-        this.right.resolve(results);
+        this.left.resolve(results, returnType);
+        this.right.resolve(results, returnType);
     }
 
     public marker(): Token {
diff --git a/src/ast_stmt.ts b/src/ast_stmt.ts
index f64b9ba..c064651 100644
--- a/src/ast_stmt.ts
+++ b/src/ast_stmt.ts
@@ -7,7 +7,7 @@ import {
     FunctionType,
     ConstantInt,
     Value,
-    ReturnInst
+    Type
 } from "llvm-bindings";
 
 import {
@@ -64,8 +64,14 @@ class StmtASTMain implements StatementAST {
     }
 
     public resolve(
-        results: ASTResolveResults
-    ): void { }
+        results: ASTResolveResults,
+        returnType: DataType
+    ): void {
+        this.body.resolve(
+            results,
+            returnType.getLLVMType() as unknown as DataType
+        );
+    }
 
     public marker(): Token {
         return this.mark;
@@ -115,8 +121,14 @@ class StmtASTRender implements StatementAST {
         );
     }
 
-    public resolve(results: ASTResolveResults): void {
-        this.expr.resolve(results);
+    public resolve(
+        results: ASTResolveResults,
+        returnType: DataType
+    ): void {
+        this.expr.resolve(
+            results,
+            returnType
+        );
     }
 
     public marker(): Token {
@@ -154,10 +166,25 @@ class StmtASTReturn implements StatementAST {
     }
 
     public resolve(
-        results: ASTResolveResults
+        results: ASTResolveResults,
+        returnType: DataType
     ): void {
-        if(this.hasValue)
-            this.value?.resolve(results);
+        if(this.hasValue) {
+            const valueType: DataType =
+                this.value?.type() as DataType;
+
+            if(valueType != returnType)
+                results.errors.set(
+                    this.mark,
+                    'Invalid return type ' +
+                    valueType.toString() + ' for type ' +
+                    returnType.toString() + '.');
+
+            this.value?.resolve(
+                results,
+                returnType
+            );
+        }
     }
 
     public marker(): Token {
diff --git a/src/data_type.ts b/src/data_type.ts
index 1f6a22c..030c763 100644
--- a/src/data_type.ts
+++ b/src/data_type.ts
@@ -30,6 +30,8 @@ class DataType {
 
     public static UNKNOWN: DataType =
         new DataType("unknown", 0, undefined);
+    public static VOID: DataType =
+        new DataType("void", 0, Type.getVoidTy(LLVMGlobalContext));
     public static STRING: DataType =
         new DataType("string", 0, undefined);
     public static BOOL: DataType =
diff --git a/src/yttria.ts b/src/yttria.ts
index e0cf8f2..631c8b8 100644
--- a/src/yttria.ts
+++ b/src/yttria.ts
@@ -1,6 +1,7 @@
 import {
     IRBuilder,
     Module,
+    Type,
     verifyModule
 } from 'llvm-bindings';
 
@@ -17,11 +18,8 @@ import {
 import {
     ExprASTAndOr,
     ExprASTBool,
-    ExprASTEquality,
     ExprASTFloat,
-    ExprASTInt,
-    ExprASTString,
-    ExprASTUnary
+    ExprASTInt
 } from './ast_expr';
 
 import {
@@ -35,6 +33,8 @@ import colors from 'colors';
 import LLVMGlobalContext from './llvm_context';
 import yargs from 'yargs';
 import YttriaUtil from './util';
+import { File } from 'buffer';
+import { DataType } from './data_type';
 
 function tokenizerTest() {
     var tokenizer = new Tokenizer(
@@ -42,6 +42,7 @@ function tokenizerTest() {
         '#hello\nsub main\n0b0101011 0xcafebabe hh 3.14 "Hello\\tworld!" +++ <<< >>>'
     );
     var tokenizerResult: TokenizerResult = tokenizer.scan();
+    const outType: Type = Type.getVoidTy(LLVMGlobalContext)
 
     if(tokenizerResult.tokens.length != 0) {
         console.log('Tokens:');
@@ -68,9 +69,14 @@ function llvmTest() {
 
     const expr1: ExprASTInt = new ExprASTInt(nullToken, BigInt('101'), 32);
     const expr2: ExprASTInt = new ExprASTInt(nullToken, BigInt('99'), 32);
+
     const cmp: ExprASTAndOr = new ExprASTAndOr(nullToken, '&', expr1, expr2);
     const body: StmtASTRender = new StmtASTRender(nullToken, cmp);
-    const main: StmtASTMain = new StmtASTMain(nullToken, body);
+
+    const main: StmtASTMain = new StmtASTMain(
+        nullToken,
+        body
+    );
 
     const builder: IRBuilder = new IRBuilder(LLVMGlobalContext);
     main.visit(builder, module);