diff -Naur lammps-13Oct09/src/fix_add_force.cpp lammps-14Oct09/src/fix_add_force.cpp
--- lammps-13Oct09/src/fix_add_force.cpp	2009-08-08 15:52:23.000000000 -0600
+++ lammps-14Oct09/src/fix_add_force.cpp	2009-10-12 10:09:55.000000000 -0600
@@ -52,7 +52,7 @@
       iregion = domain->find_region(arg[iarg+1]);
       if (iregion == -1) error->all("Fix addforce region ID does not exist");
       iarg += 2;
-    }
+    } else error->all("Illegal fix addforce command");
   }
 
   force_flag = 0;
diff -Naur lammps-13Oct09/src/fix_ave_force.cpp lammps-14Oct09/src/fix_ave_force.cpp
--- lammps-13Oct09/src/fix_ave_force.cpp	2009-08-08 15:52:23.000000000 -0600
+++ lammps-14Oct09/src/fix_ave_force.cpp	2009-10-12 10:09:55.000000000 -0600
@@ -55,7 +55,8 @@
       iregion = domain->find_region(arg[iarg+1]);
       if (iregion == -1) error->all("Fix aveforce region ID does not exist");
       iarg += 2;
-    }
+    } else error->all("Illegal fix aveforce command");
+
   }
 
   foriginal_all[0] = foriginal_all[1] =