diff --git a/src/USER-OMP/fix_omp.cpp b/src/USER-OMP/fix_omp.cpp
index e3adb6c268..20e60bab26 100644
--- a/src/USER-OMP/fix_omp.cpp
+++ b/src/USER-OMP/fix_omp.cpp
@@ -105,6 +105,7 @@ FixOMP::FixOMP(LAMMPS *lmp, int narg, char **arg)
   // print summary of settings
 
   if (comm->me == 0) {
+#if defined(_OPENMP)
     const char * const nmode = _neighbor ? "multi-threaded" : "serial";
 
     if (screen) {
@@ -118,6 +119,10 @@ FixOMP::FixOMP(LAMMPS *lmp, int narg, char **arg)
 	fprintf(logfile,"set %d OpenMP thread(s) per MPI task\n", nthreads);
       fprintf(logfile,"using %s neighbor list subroutines\n", nmode);
     }
+#else
+    error->warning(FLERR,"OpenMP support not enabled during compilation; "
+                         "using 1 thread only.");
+#endif
   }
 
   // allocate list for per thread accumulator manager class instances
diff --git a/src/comm.cpp b/src/comm.cpp
index f29d1bf7df..070fd8575a 100644
--- a/src/comm.cpp
+++ b/src/comm.cpp
@@ -87,7 +87,8 @@ Comm::Comm(LAMMPS *lmp) : Pointers(lmp)
   } else if (getenv("OMP_NUM_THREADS") == NULL) {
     nthreads = 1;
     if (me == 0)
-      error->warning(FLERR,"OMP_NUM_THREADS environment is not set.");
+      error->warning(FLERR,"OMP_NUM_THREADS environment is not set. "
+                           "Defaulting to 1 thread.");
   } else {
     nthreads = omp_get_max_threads();
   }