diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 410c336..ab933fe 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -3176,6 +3176,7 @@
 	list_del_rcu(&class->hash_entry);
 	list_del_rcu(&class->lock_entry);
 
+	class->key = NULL;
 }
 
 static inline int within(const void *addr, void *start, unsigned long size)