diff --git a/src/mark_sweep.cc b/src/mark_sweep.cc
index 79597ec..6512aef 100644
--- a/src/mark_sweep.cc
+++ b/src/mark_sweep.cc
@@ -269,7 +269,7 @@
     } else if (klass->IsPhantomReferenceClass()) {
       list = &phantom_reference_list_;
     }
-    DCHECK(list != NULL);
+    DCHECK(list != NULL) << PrettyClass(klass) << " " << std::hex << klass->GetAccessFlags();
     Heap::EnqueuePendingReference(obj, list);
   }
 }