--- a/scripts/prefs/rmpref.m
+++ b/scripts/prefs/rmpref.m
@@ -17,14 +17,15 @@
 ## <http://www.gnu.org/licenses/>.
 
 ## -*- texinfo -*-
-## @deftypefn {Function File} {} rmpref (@var{group}, @var{pref})
+## @deftypefn  {Function File} {} rmpref (@var{group})
+## @deftypefnx {Function File} {} rmpref (@var{group}, @var{pref})
 ## Remove the named preference @var{pref} from the preference group
 ## @var{group}.
 ##
 ## The named preference group must be a character string.
 ##
-## The preference @var{pref} may be a character string or a cell array
-## of character strings.
+## The preference @var{pref} may be a character string or cell array
+## of strings.
 ##
 ## If @var{pref} is not specified, remove the preference group
 ## @var{group}.
@@ -37,25 +38,48 @@
 
 function retval = rmpref (group, pref)
 
-  prefs = loadprefs ();
+  if (nargin < 1 || nargin > 2)
+    print_usage ();
+  elseif (! ischar (group))
+    error ("rmpref: GROUP must be a string");
+  elseif (nargin == 2 && ! (ischar (pref) || iscellstr (pref)))
+    error ("rmpref: PREF must be a string or cell array of strings");
+  endif
 
   if (nargin == 1)
-    if (ischar (group))
-      retval = isfield (prefs, group);
+    if (ispref (group))
+      prefs = loadprefs ();
+      prefs = rmfield (prefs, group);
+      saveprefs (prefs);
     else
-      error ("expecting group to be a character array");
-    endif
-  elseif (nargin == 2)
-    grp = getpref (group, pref);
-    if (ischar (pref) || iscellstr (pref))
-      retval = isfield (grp, pref);
+      error ("rmpref: group <%s> does not exist", group);
     endif
   else
-    print_usage ();
+    valid = ispref (group, pref);
+    if (all (valid))
+      prefs = loadprefs ();
+      prefs.(group) = rmfield (prefs.(group), pref);
+      saveprefs (prefs);
+    else
+      if (! ispref (group))
+        error ("rmpref: group <%s> does not exist", group);
+      else
+        idx = find (! valid, 1); 
+        error ("rmpref: pref <%s> does not exist", (cellstr (pref)){idx} );
+      endif
+    endif
   endif
 
 endfunction
 
-%% Testing these functions will require some care to avoid wiping out
-%% existing (or creating unwanted) preferences for the user running the
-%% tests.
+
+## Testing these functions will require some care to avoid wiping out
+## existing (or creating unwanted) preferences for the user running the
+## tests.
+
+## Test input validation
+%!error rmpref ()
+%!error rmpref (1,2,3)
+%!error rmpref ({"__group1__"})
+%!error rmpref ("__group1__", 1)
+