diff --git a/src/atom.cpp b/src/atom.cpp
index 9a9ff5957d..1992ca17ac 100644
--- a/src/atom.cpp
+++ b/src/atom.cpp
@@ -162,7 +162,7 @@ Atom::Atom(LAMMPS *lmp) : Pointers(lmp)
   tag_enable = 1;
   map_style = map_user = 0;
   map_tag_max = -1;
-  map_maxarray = map_nhash = 0;
+  map_maxarray = map_nhash = -1;
 
   max_same = 0;
   sametag = NULL;
@@ -480,6 +480,7 @@ void Atom::modify_params(int narg, char **arg)
       if (strcmp(arg[iarg+1],"array") == 0) map_user = 1;
       else if (strcmp(arg[iarg+1],"hash") == 0) map_user = 2;
       else error->all(FLERR,"Illegal atom_modify command");
+      map_style = map_user;
       iarg += 2;
     } else if (strcmp(arg[iarg],"first") == 0) {
       if (iarg+2 > narg) error->all(FLERR,"Illegal atom_modify command");
diff --git a/src/atom_map.cpp b/src/atom_map.cpp
index d209754717..a63db79cce 100644
--- a/src/atom_map.cpp
+++ b/src/atom_map.cpp
@@ -37,6 +37,7 @@ void Atom::map_init(int check)
   // check for new map style if max atomID changed (check = 1 = default)
   // recreate = 1 if must delete old map and create new map
   // recreate = 0 if can re-use old map w/out realloc and just adjust settings
+  // map_maxarray/map_nhash initially -1, to force recreate even when no atoms
 
   int recreate = 0;
   if (check) recreate = map_style_set();