diff --git a/src/fix_enforce2d.cpp b/src/fix_enforce2d.cpp
index 8d0f1a123d..45b77cbf35 100644
--- a/src/fix_enforce2d.cpp
+++ b/src/fix_enforce2d.cpp
@@ -45,7 +45,7 @@ int FixEnforce2D::setmask()
 void FixEnforce2D::init()
 {
   if (domain->dimension == 3)
-    error->all("Should not use fix enforce2d with 3d simulation");
+    error->all("Cannot use fix enforce2d with 3d simulation");
 }
 
 /* ---------------------------------------------------------------------- */
diff --git a/src/fix_nph.cpp b/src/fix_nph.cpp
index c754b3bd1d..1190b65a54 100644
--- a/src/fix_nph.cpp
+++ b/src/fix_nph.cpp
@@ -139,21 +139,21 @@ FixNPH::FixNPH(LAMMPS *lmp, int narg, char **arg) :
   // error checks
 
   if (press_couple == XY && (p_flag[0] == 0 || p_flag[1] == 0))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix nph command pressure settings");
   if (press_couple == YZ && (p_flag[1] == 0 || p_flag[2] == 0))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix nph command pressure settings");
   if (press_couple == XZ && (p_flag[0] == 0 || p_flag[2] == 0))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix nph command pressure settings");
 
   if (press_couple == XY && 
       (p_start[0] != p_start[1] || p_stop[0] != p_stop[1]))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix nph command pressure settings");
   if (press_couple == YZ && 
       (p_start[1] != p_start[2] || p_stop[1] != p_stop[2]))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix nph command pressure settings");
   if (press_couple == XZ && 
       (p_start[0] != p_start[2] || p_stop[0] != p_stop[2]))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix nph command pressure settings");
 
   if (p_flag[0] && domain->xperiodic == 0)
     error->all("Cannot use fix nph on a non-periodic dimension");
diff --git a/src/fix_npt.cpp b/src/fix_npt.cpp
index 1bb3de291a..2a3e1942af 100644
--- a/src/fix_npt.cpp
+++ b/src/fix_npt.cpp
@@ -145,21 +145,21 @@ FixNPT::FixNPT(LAMMPS *lmp, int narg, char **arg) :
   // error checks
 
   if (press_couple == XY && (p_flag[0] == 0 || p_flag[1] == 0))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix npt command pressure settings");
   if (press_couple == YZ && (p_flag[1] == 0 || p_flag[2] == 0))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix npt command pressure settings");
   if (press_couple == XZ && (p_flag[0] == 0 || p_flag[2] == 0))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix npt command pressure settings");
 
   if (press_couple == XY && 
       (p_start[0] != p_start[1] || p_stop[0] != p_stop[1]))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix npt command pressure settings");
   if (press_couple == YZ && 
       (p_start[1] != p_start[2] || p_stop[1] != p_stop[2]))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix npt command pressure settings");
   if (press_couple == XZ && 
       (p_start[0] != p_start[2] || p_stop[0] != p_stop[2]))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix npt command pressure settings");
     
   if (p_flag[0] && domain->xperiodic == 0)
     error->all("Cannot use fix npt on a non-periodic dimension");
diff --git a/src/fix_press_berendsen.cpp b/src/fix_press_berendsen.cpp
index 31f200976c..a4b69cd7b6 100644
--- a/src/fix_press_berendsen.cpp
+++ b/src/fix_press_berendsen.cpp
@@ -135,21 +135,21 @@ FixPressBerendsen::FixPressBerendsen(LAMMPS *lmp, int narg, char **arg) :
   // error checks
 
   if (press_couple == XY && (p_flag[0] == 0 || p_flag[1] == 0))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix press/berendsen command pressure settings");
   if (press_couple == YZ && (p_flag[1] == 0 || p_flag[2] == 0))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix press/berendsen command pressure settings");
   if (press_couple == XZ && (p_flag[0] == 0 || p_flag[2] == 0))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix press/berendsen command pressure settings");
 
   if (press_couple == XY && 
       (p_start[0] != p_start[1] || p_stop[0] != p_stop[1]))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix press/berendsen command pressure settings");
   if (press_couple == YZ && 
       (p_start[1] != p_start[2] || p_stop[1] != p_stop[2]))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix press/berendsen command pressure settings");
   if (press_couple == XZ && 
       (p_start[0] != p_start[2] || p_stop[0] != p_stop[2]))
-    error->all("Invalid fix npt command");
+    error->all("Invalid fix press/berendsen command pressure settings");
 
   if (p_flag[0] && domain->xperiodic == 0)
     error->all("Cannot use fix press/berendsen on a non-periodic dimension");