diff --git a/modules/bindings/pymod/msms.py b/modules/bindings/pymod/msms.py
index a7a3dd13eb2be594c69f0fb368c941ce403dfd7a..7f9e089ffe63b92f036fe35151593205b25ae6c9 100644
--- a/modules/bindings/pymod/msms.py
+++ b/modules/bindings/pymod/msms.py
@@ -144,7 +144,10 @@ def CalculateSurfaceArea(entity, density=1.0, radius=1.5,  all_surf=False,
 
   # parse selection
   if no_hydrogens:
-    selection+=" and ele!=H"
+    if selection=="":
+      selection="ele!=H"
+    else:
+      selection+=" and ele!=H"
 
   # setup files for msms
   (msms_data_dir, msms_data_file)=_SetupFiles(entity, selection)
@@ -215,7 +218,10 @@ def CalculateSurface(entity, density=1.0, radius=1.5, all_surf=False,
 
   # parse selection
   if no_hydrogens:
-    selection+=" and ele!=H"
+    if selection=="":
+      selection="ele!=H"
+    else:
+      selection+=" and ele!=H"
 
   # setup files for msms