diff --git a/src/rgw/rgw_rados.cc b/src/rgw/rgw_rados.cc
index 80ebc273c0f..5324654f5e8 100644
--- a/src/rgw/rgw_rados.cc
+++ b/src/rgw/rgw_rados.cc
@@ -4863,7 +4863,7 @@ int RGWRados::time_log_trim(const string& oid, const real_time& start_time, cons
 string RGWRados::objexp_hint_get_shardname(int shard_num)
 {
   char buf[32];
-  snprintf(buf, sizeof(buf), "%010u", shard_num);
+  snprintf(buf, sizeof(buf), "%010u", (unsigned)shard_num);
 
   string objname("obj_delete_at_hint.");
   return objname + buf;