diff --git a/src/main/java/de/dhbwstuttgart/target/bytecode/Codegen.java b/src/main/java/de/dhbwstuttgart/target/bytecode/Codegen.java
index 71cbb1f9..e1744b4d 100755
--- a/src/main/java/de/dhbwstuttgart/target/bytecode/Codegen.java
+++ b/src/main/java/de/dhbwstuttgart/target/bytecode/Codegen.java
@@ -58,8 +58,10 @@ public class Codegen {
         Scope scope = new Scope(null);
         int localCounter;
         MethodVisitor mv;
+        TargetType returnType;
 
-        State(MethodVisitor mv, int localCounter) {
+        State(TargetType returnType, MethodVisitor mv, int localCounter) {
+            this.returnType = returnType;
             this.mv = mv;
             this.localCounter = localCounter;
         }
@@ -832,13 +834,15 @@ public class Codegen {
                         break;
                     }
                     case TargetFieldVar dot: {
+                        var fieldType = dot.type();
                         generate(state, dot.left());
                         generate(state, assign.right());
-                        boxPrimitive(state, assign.right().type());
+                        convertTo(state, assign.right().type(), fieldType);
+                        boxPrimitive(state, fieldType);
                         if (dot.isStatic())
                             mv.visitInsn(DUP);
                         else mv.visitInsn(DUP_X1);
-                        mv.visitFieldInsn(dot.isStatic() ? PUTSTATIC : PUTFIELD, dot.owner().getInternalName(), dot.right(), dot.type().toSignature());
+                        mv.visitFieldInsn(dot.isStatic() ? PUTSTATIC : PUTFIELD, dot.owner().getInternalName(), dot.right(), fieldType.toSignature());
                         break;
                     }
                     default:
@@ -911,7 +915,8 @@ public class Codegen {
             case TargetReturn ret: {
                 if (ret.expression() != null) {
                     generate(state, ret.expression());
-                    boxPrimitive(state, ret.expression().type());
+                    convertTo(state, ret.expression().type(), state.returnType);
+                    boxPrimitive(state, state.returnType);
                     mv.visitInsn(ARETURN);
                 } else mv.visitInsn(RETURN);
                 break;
@@ -975,7 +980,7 @@ public class Codegen {
     private void generateConstructor(TargetConstructor constructor) {
         MethodVisitor mv = cw.visitMethod(constructor.access() | ACC_PUBLIC, "<init>", constructor.getDescriptor(), constructor.getSignature(), null);
         mv.visitCode();
-        var state = new State(mv, 1);
+        var state = new State(null, mv, 1);
         for (var param: constructor.parameters())
             state.createVariable(param.name(), param.type());
 
@@ -999,7 +1004,7 @@ public class Codegen {
         // TODO The older codegen has set ACC_PUBLIC for all methods, good for testing but bad for everything else
         MethodVisitor mv = cw.visitMethod(method.access() | ACC_PUBLIC, method.name(), method.getDescriptor(), method.getSignature(), null);
         mv.visitCode();
-        var state = new State(mv, method.isStatic() ? 0 : 1);
+        var state = new State(method.returnType(), mv, method.isStatic() ? 0 : 1);
         for (var param: method.parameters())
             state.createVariable(param.name(), param.type());
         generate(state, method.block());
diff --git a/src/test/resources/bytecode/javFiles/Box.java b/src/test/resources/bytecode/javFiles/Box.java
new file mode 100644
index 00000000..e69de29b