diff --git a/doc/src/fix_atom_swap.rst b/doc/src/fix_atom_swap.rst
index aa8127561c..8810ae9cf9 100644
--- a/doc/src/fix_atom_swap.rst
+++ b/doc/src/fix_atom_swap.rst
@@ -21,7 +21,7 @@ Syntax
 
   .. parsed-literal::
 
-       *types* values = two or more atom types
+       *types* values = two or more atom types (1-Ntypes or type label)
        *mu* values = chemical potential of swap types (energy units)
        *ke* value = *no* or *yes*
          *no* = no conservation of kinetic energy after atom swaps
diff --git a/src/MC/fix_atom_swap.cpp b/src/MC/fix_atom_swap.cpp
index 6fe0ac98b7..8807de18ad 100644
--- a/src/MC/fix_atom_swap.cpp
+++ b/src/MC/fix_atom_swap.cpp
@@ -171,7 +171,7 @@ void FixAtomSwap::options(int narg, char **arg)
       while (iarg < narg) {
         if (isalpha(arg[iarg][0])) break;
         if (nswaptypes >= atom->ntypes) error->all(FLERR, "Illegal fix atom/swap command");
-        type_list[nswaptypes] = utils::numeric(FLERR, arg[iarg], false, lmp);
+        type_list[nswaptypes] = utils::expand_type_int(FLERR, arg[iarg], Atom::ATOM, lmp);
         nswaptypes++;
         iarg++;
       }