diff --git a/src/p3m.c b/src/p3m.c
index 418352b22dc..b2aedb716e7 100644
--- a/src/p3m.c
+++ b/src/p3m.c
@@ -389,7 +389,7 @@ void p3m_set_tune_params(double r_cut, int mesh, int cao,
 
 /*@}*/
 
-int p3m_set_params(double r_cut, int mesh, int cao,
+int p3m_set_params(double r_cut, int *mesh, int cao,
 		   double alpha, double accuracy)
 {
   if (coulomb.method != COULOMB_P3M && coulomb.method != COULOMB_ELC_P3M)
@@ -398,15 +398,17 @@ int p3m_set_params(double r_cut, int mesh, int cao,
   if(r_cut < 0)
     return -1;
 
-  if(mesh < 0)
+  if((mesh[0] < 0) || (mesh[1] < 0) || (mesh[2] < 0))
     return -2;
 
-  if(cao < 1 || cao > 7 || cao > mesh)
+  if(cao < 1 || cao > 7 || cao > mesh[0] || cao > mesh[1] || cao > mesh[2] )
     return -3;
 
   p3m.params.r_cut    = r_cut;
   p3m.params.r_cut_iL = r_cut*box_l_i[0];
-  p3m.params.mesh[2]  = p3m.params.mesh[1] = p3m.params.mesh[0] = mesh;
+  p3m.params.mesh[2]  = mesh[2];
+  p3m.params.mesh[1] = mesh[1];
+  p3m.params.mesh[0] = mesh[0];
   p3m.params.cao      = cao;
 
   if (alpha > 0) {
diff --git a/src/p3m.h b/src/p3m.h
index 146317f04b3..4e99eaa0a80 100644
--- a/src/p3m.h
+++ b/src/p3m.h
@@ -240,7 +240,7 @@ MDINLINE double p3m_add_pair_force(double chgfac, double *d,double dist2,double
 void p3m_set_tune_params(double r_cut, int mesh, int cao,
 			 double alpha, double accuracy, int n_interpol);
 
-int p3m_set_params(double r_cut, int mesh, int cao,
+int p3m_set_params(double r_cut, int *mesh, int cao,
 		   double alpha, double accuracy);
 
 int p3m_set_mesh_offset(double x, double y, double z);
diff --git a/src/tcl/p3m_tcl.c b/src/tcl/p3m_tcl.c
index ad9c3d9ea06..6f008f38cf3 100644
--- a/src/tcl/p3m_tcl.c
+++ b/src/tcl/p3m_tcl.c
@@ -99,7 +99,9 @@ int tclcommand_inter_coulomb_parse_p3m_tune(Tcl_Interp * interp, int argc, char
 int tclcommand_inter_coulomb_parse_p3m(Tcl_Interp * interp, int argc, char ** argv)
 {
   double r_cut, alpha, accuracy = -1.0;
-  int mesh, cao, i;
+  int mesh[3], cao, i;
+  IntList il;
+  init_intlist(&il);
 
   if (argc < 1) {
     Tcl_AppendResult(interp, "expected: inter coulomb <bjerrum> p3m tune | <r_cut> <mesh> <cao> [<alpha> [<accuracy>]]",
@@ -117,12 +119,25 @@ int tclcommand_inter_coulomb_parse_p3m(Tcl_Interp * interp, int argc, char ** ar
     return TCL_ERROR;  
 
   if(argc < 3 || argc > 5) {
-    Tcl_AppendResult(interp, "wrong # arguments: inter coulomb <bjerrum> p3m <r_cut> <mesh> <cao> [<alpha> [<accuracy>]]",
+    Tcl_AppendResult(interp, "wrong # arguments: inter coulomb <bjerrum> p3m <r_cut> { <mesh> | \\{ <mesh_x> <mesh_y> <mesh_z> \\} } <cao> [<alpha> [<accuracy>]]",
 		     (char *) NULL);
     return TCL_ERROR;  
   }
 
-  if((! ARG_IS_I(1, mesh)) || (! ARG_IS_I(2, cao))) {
+  if(! ARG_IS_I(1, mesh[0])) {
+    if( ! ARG_IS_INTLIST(1, il) || !(il.n == 3) ) {
+      Tcl_AppendResult(interp, "integer or interger list of length 3 expected", (char *) NULL);
+      return TCL_ERROR;
+    } else {
+      mesh[0] = il.e[0];
+      mesh[1] = il.e[1];
+      mesh[2] = il.e[2];
+    }
+  } else {
+    mesh[1] = mesh[2] = mesh[0];
+  }
+
+  if(! ARG_IS_I(2, cao)) {
     Tcl_AppendResult(interp, "integer expected", (char *) NULL);
     return TCL_ERROR;
   }