diff --git a/runtime/stack.cc b/runtime/stack.cc
index d570880..97a8d01 100644
--- a/runtime/stack.cc
+++ b/runtime/stack.cc
@@ -134,7 +134,8 @@
     } else {
       return cur_shadow_frame_->GetVRegReference(0);
     }
-  } else if (m->IsOptimized(sizeof(void*))) {
+  } else if (m->IsOptimized(GetInstructionSetPointerSize(
+      Runtime::Current()->GetInstructionSet()))) {
     // TODO: Implement, currently only used for exceptions when jdwp is enabled.
     UNIMPLEMENTED(WARNING)
         << "StackVisitor::GetThisObject is unimplemented with the optimizing compiler";