--- old/src/hotspot/share/prims/jvm.cpp	2018-05-21 11:52:13.892095230 +0200
+++ new/src/hotspot/share/prims/jvm.cpp	2018-05-21 11:52:13.584089742 +0200
@@ -653,6 +653,7 @@
     ResourceMark rm(THREAD);
     THROW_MSG_0(vmSymbols::java_lang_CloneNotSupportedException(), klass->external_name());
   }
+  assert(!EnableValhalla || !obj->klass()->is_value(), "Clone disallowed on value type");
 
   // Make shallow object copy
   const int size = obj->size();