--- a/src/hotspot/share/jfr/recorder/checkpoint/jfrCheckpointManager.cpp	Mon Oct 22 12:25:31 2018 +0100
+++ b/src/hotspot/share/jfr/recorder/checkpoint/jfrCheckpointManager.cpp	Mon Oct 22 12:13:29 2018 +0200
@@ -367,7 +367,7 @@
 }
 
 void JfrCheckpointManager::write_type_set_for_unloaded_classes() {
-  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint!");
+  assert_locked_or_safepoint(ClassLoaderDataGraph_lock);
   JfrTypeManager::write_type_set_for_unloaded_classes();
 }