diff --git a/src/USER-MISC/pair_list.cpp b/src/USER-MISC/pair_list.cpp
index d1e2e93ce1..d23215a9b9 100644
--- a/src/USER-MISC/pair_list.cpp
+++ b/src/USER-MISC/pair_list.cpp
@@ -375,6 +375,9 @@ void PairList::init_style()
   if (atom->tag_enable == 0)
     error->all(FLERR,"Pair style list requires atom IDs");
 
+  if (atom->map_style == 0)
+    error->all(FLERR,"Pair style list requires an atom map");
+
   if (offset_flag) {
     for (int n=0; n < npairs; ++n) {
       list_parm_t &par = params[n];
diff --git a/src/USER-MISC/pair_list.h b/src/USER-MISC/pair_list.h
index 8869a52f52..9d199f5ba7 100644
--- a/src/USER-MISC/pair_list.h
+++ b/src/USER-MISC/pair_list.h
@@ -74,5 +74,43 @@ class PairList : public Pair {
 
 /* ERROR/WARNING messages:
 
+E: Not all pairs processed in pair_style list
+
+Not all interacting pairs for which coefficients were found. This can be intentional
+and then you need to set the 'nocheck' option. If not, it usually means that the 
+communication cutoff is too small. This can be ameliorated by either increasing
+the cutoff in the pair_style command or the communication cutoff.
+
+E: Illegal ... command
+
+Self-explanatory.  Check the input script syntax and compare to the
+documentation for the command.  You can use -echo screen as a
+command-line option when running LAMMPS to see the offending line.
+
+E: Cannot open pair list file
+
+Self-explanatory.  The file with the list of pairs cannot be open for reading.
+Check the path and permissions.
+
+E: Incorrectly formatted ...
+
+Self-explanatory.  The content of the pair list file does not match the documented
+format. Please re-read the documentation and carefully compare it to your file.
+
+E: Unknown pair list potential style
+
+Self-explanatory.  You requested a potential type that is not yet implemented or have a typo.
+
+E: Incorrect args for pair coefficients
+
+Self-explanatory.  Check the input script or data file.
+
+E: Pair style list requires atom IDs
+
+Self-explanatory.  The pairs in the list are identified via atom IDs, so they need to be present.
+
+E: Pair style list requires an atom map
+
+Self-explanatory.  Atoms are looked up via an atom map. Create one using the atom_style map command.
 
 */
diff --git a/src/atom.h b/src/atom.h
index 375417942f..4d617585ae 100644
--- a/src/atom.h
+++ b/src/atom.h
@@ -1,4 +1,4 @@
-/* ----------------------------------------------------------------------
+/* -*- c++ -*- ----------------------------------------------------------
    LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
    http://lammps.sandia.gov, Sandia National Laboratories
    Steve Plimpton, sjplimp@sandia.gov
@@ -185,10 +185,12 @@ class Atom : protected Pointers {
 
   // functions for global to local ID mapping
   // map lookup function inlined for efficiency
+  // return -1 if no map defined
 
   inline int map(int global) {
     if (map_style == 1) return map_array[global];
-    else return map_find_hash(global);
+    else if (map_style == 2) return map_find_hash(global);
+    else return -1;
   };
 
   void map_init();