diff --git a/src/metadata/metadataVisitor.ts b/src/metadata/metadataVisitor.ts
index e345426..368ed05 100644
--- a/src/metadata/metadataVisitor.ts
+++ b/src/metadata/metadataVisitor.ts
@@ -15,23 +15,48 @@ export function metadataVisitor(
         field.kind === 'constructor' ? classNode.decorators : field.decorators;
 
       if (!decorators || decorators.length === 0) return;
-
-      decorators!.push(
-        t.decorator(
-          t.callExpression(
-            t.memberExpression(
-              t.identifier('Reflect'),
-              t.identifier('metadata')
-            ),
-            [
-              t.stringLiteral('design:paramtypes'),
-              t.arrayExpression(
-                field.params.map(param => serializeType(classPath, param))
-              )
-            ]
+      if(field.kind === 'get') {
+        field.decorators!.push(
+          t.decorator(
+            t.callExpression(
+              t.memberExpression(
+                t.identifier('Reflect'),
+                t.identifier('metadata')
+              ),
+              [t.stringLiteral('design:type'), serializeType(classPath, field.returnType)]
+            )
           )
-        )
-      );
+        );
+      } else if(field.kind === 'set') {
+        field.decorators!.push(
+          t.decorator(
+            t.callExpression(
+              t.memberExpression(
+                t.identifier('Reflect'),
+                t.identifier('metadata')
+              ),
+              [t.stringLiteral('design:type'), field.params.map(param => serializeType(classPath, param)).reduce(value => value)]
+            )
+          )
+        );
+      } else {
+        decorators!.push(
+          t.decorator(
+            t.callExpression(
+              t.memberExpression(
+                t.identifier('Reflect'),
+                t.identifier('metadata')
+              ),
+              [
+                t.stringLiteral('design:paramtypes'),
+                t.arrayExpression(
+                  field.params.map(param => serializeType(classPath, param))
+                )
+              ]
+            )
+          )
+        );
+      }
       break;
 
     case 'ClassProperty':
diff --git a/src/metadata/serializeType.ts b/src/metadata/serializeType.ts
index a60cc0e..96a407e 100644
--- a/src/metadata/serializeType.ts
+++ b/src/metadata/serializeType.ts
@@ -3,7 +3,7 @@ import { NodePath } from '@babel/traverse';
 
 type InferArray<T> = T extends Array<infer A> ? A : never;
 
-type Parameter = InferArray<t.ClassMethod['params']> | t.ClassProperty;
+type Parameter = InferArray<t.ClassMethod['params']> | t.ClassProperty | t.ClassMethod['returnType'];
 
 function createVoidZero() {
   return t.unaryExpression('void', t.numericLiteral(0));
@@ -16,7 +16,7 @@ function createVoidZero() {
  * @todo Array and Objects spread are not supported.
  * @todo Rest parameters are not supported.
  */
-function getTypedNode(param: Parameter): t.Identifier | t.ClassProperty | null {
+function getTypedNode(param: Parameter): t.Identifier | t.ClassProperty | t.TSTypeAnnotation | null {
   if (param == null) return null;
 
   if (param.type === 'ClassProperty') return param;
@@ -28,6 +28,9 @@ function getTypedNode(param: Parameter): t.Identifier | t.ClassProperty | null {
   if (param.type === 'TSParameterProperty')
     return getTypedNode(param.parameter);
 
+  if (param.type === 'TSTypeAnnotation')
+    return param;
+  
   return null;
 }
 
@@ -38,12 +41,17 @@ export function serializeType(
   const node = getTypedNode(param);
   if (node == null) return createVoidZero();
 
-  if (!node.typeAnnotation || node.typeAnnotation.type !== 'TSTypeAnnotation')
+  if (!node.typeAnnotation || (node.typeAnnotation.type !== 'TSTypeAnnotation' && node.type !== 'TSTypeAnnotation'))
     return createVoidZero();
-
-  const annotation = node.typeAnnotation.typeAnnotation;
-  const className = classPath.node.id ? classPath.node.id.name : '';
-  return serializeTypeNode(className, annotation);
+  if(node.type === 'TSTypeAnnotation') {
+    const annotation = node.typeAnnotation;
+    const className = classPath.node.id ? classPath.node.id.name : '';
+    return serializeTypeNode(className, annotation);
+  } else {
+    const annotation = (<any>node).typeAnnotation.typeAnnotation;
+    const className = classPath.node.id ? classPath.node.id.name : '';
+    return serializeTypeNode(className, annotation);
+  }
 }
 
 function serializeTypeReferenceNode(