diff --git a/src/mds/FSMap.cc b/src/mds/FSMap.cc
index 55c72f2addc..bfa97a3d6fd 100644
--- a/src/mds/FSMap.cc
+++ b/src/mds/FSMap.cc
@@ -787,6 +787,8 @@ bool FSMap::undamaged(const fs_cluster_id_t fscid, const mds_rank_t rank)
 
 void FSMap::insert(const MDSMap::mds_info_t &new_info)
 {
+  assert(new_info.state == MDSMap::STATE_STANDBY);
+  assert(new_info.rank == MDS_RANK_NONE);
   mds_roles[new_info.global_id] = FS_CLUSTER_ID_NONE;
   standby_daemons[new_info.global_id] = new_info;
   standby_epochs[new_info.global_id] = epoch;
diff --git a/src/mds/FSMap.h b/src/mds/FSMap.h
index d14e365a652..5bf27838be6 100644
--- a/src/mds/FSMap.h
+++ b/src/mds/FSMap.h
@@ -311,7 +311,9 @@ public:
       std::function<void(MDSMap::mds_info_t *info)> fn)
   {
     if (mds_roles.at(who) == FS_CLUSTER_ID_NONE) {
-      fn(&standby_daemons.at(who));
+      auto &info = standby_daemons.at(who);
+      fn(&info);
+      assert(info.state == MDSMap::STATE_STANDBY);
       standby_epochs[who] = epoch;
     } else {
       auto fs = filesystems[mds_roles.at(who)];