--- old/src/hotspot/share/runtime/biasedLocking.cpp	2019-03-11 14:27:08.802354289 +0100
+++ new/src/hotspot/share/runtime/biasedLocking.cpp	2019-03-11 14:27:08.594354292 +0100
@@ -49,7 +49,9 @@
 static GrowableArray<markOop>* _preserved_mark_stack = NULL;
 
 static void enable_biased_locking(InstanceKlass* k) {
-  k->set_prototype_header(markOopDesc::biased_locking_prototype());
+  if (!k->is_value()) {
+    k->set_prototype_header(markOopDesc::biased_locking_prototype());
+  }
 }
 
 class VM_EnableBiasedLocking: public VM_Operation {