diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
index e3b848d..30acc7b 100644
--- a/fs/ceph/caps.c
+++ b/fs/ceph/caps.c
@@ -586,6 +586,7 @@
 		} else {
 			pr_err("ceph_add_cap: couldn't find snap realm %llx\n",
 			       realmino);
+			WARN_ON(!realm);
 		}
 	}