diff --git a/src/runtime/runtime-proxy.cc b/src/runtime/runtime-proxy.cc
index 7764d25..87c7c91 100644
--- a/src/runtime/runtime-proxy.cc
+++ b/src/runtime/runtime-proxy.cc
@@ -40,17 +40,15 @@
       Object::GetMethod(Handle<JSReceiver>::cast(handler), trap_name));
   // 6. If trap is undefined, then
   int const arguments_length = args.length() - 2;
-  if (trap->IsUndefined()) {
+  if (trap->IsUndefined(isolate)) {
     // 6.a. Return Call(target, thisArgument, argumentsList).
     ScopedVector<Handle<Object>> argv(arguments_length);
     for (int i = 0; i < arguments_length; ++i) {
       argv[i] = args.at<Object>(i + 1);
     }
-    Handle<Object> result;
-    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-        isolate, result, Execution::Call(isolate, target, receiver,
-                                         arguments_length, argv.start()));
-    return *result;
+    RETURN_RESULT_OR_FAILURE(
+        isolate, Execution::Call(isolate, target, receiver, arguments_length,
+                                 argv.start()));
   }
   // 7. Let argArray be CreateArrayFromList(argumentsList).
   Handle<JSArray> arg_array = isolate->factory()->NewJSArray(
@@ -63,12 +61,10 @@
     }
   }
   // 8. Return Call(trap, handler, «target, thisArgument, argArray»).
-  Handle<Object> trap_result;
   Handle<Object> trap_args[] = {target, receiver, arg_array};
-  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-      isolate, trap_result,
+  RETURN_RESULT_OR_FAILURE(
+      isolate,
       Execution::Call(isolate, trap, handler, arraysize(trap_args), trap_args));
-  return *trap_result;
 }
 
 
@@ -98,7 +94,7 @@
       Object::GetMethod(Handle<JSReceiver>::cast(handler), trap_name));
   // 6. If trap is undefined, then
   int const arguments_length = args.length() - 3;
-  if (trap->IsUndefined()) {
+  if (trap->IsUndefined(isolate)) {
     // 6.a. Assert: target has a [[Construct]] internal method.
     DCHECK(target->IsConstructor());
     // 6.b. Return Construct(target, argumentsList, newTarget).
@@ -106,11 +102,9 @@
     for (int i = 0; i < arguments_length; ++i) {
       argv[i] = args.at<Object>(i + 1);
     }
-    Handle<Object> result;
-    ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-        isolate, result, Execution::New(isolate, target, new_target,
-                                        arguments_length, argv.start()));
-    return *result;
+    RETURN_RESULT_OR_FAILURE(
+        isolate, Execution::New(isolate, target, new_target, arguments_length,
+                                argv.start()));
   }
   // 7. Let argArray be CreateArrayFromList(argumentsList).
   Handle<JSArray> arg_array = isolate->factory()->NewJSArray(