diff --git a/src/common/ceph_json.h b/src/common/ceph_json.h
index 85f3f3656e0..b3961cc7832 100644
--- a/src/common/ceph_json.h
+++ b/src/common/ceph_json.h
@@ -38,7 +38,7 @@ public:
   void operator++();
   JSONObj *operator*();
 
-  bool end() {
+  bool end() const {
     return (cur == last);
   }
 };