SF patch #474590 -- RISC OS support
diff --git a/Lib/dumbdbm.py b/Lib/dumbdbm.py
index 287a8a0..d5df1d5 100644
--- a/Lib/dumbdbm.py
+++ b/Lib/dumbdbm.py
@@ -33,13 +33,9 @@
 class _Database:
 
     def __init__(self, file):
-        if _os.sep == '.':
-            endsep = '/'
-        else:
-            endsep = '.'
-        self._dirfile = file + endsep + 'dir'
-        self._datfile = file + endsep + 'dat'
-        self._bakfile = file + endsep + 'bak'
+        self._dirfile = file + _os.extsep + 'dir'
+        self._datfile = file + _os.extsep + 'dat'
+        self._bakfile = file + _os.extsep + 'bak'
         # Mod by Jack: create data file if needed
         try:
             f = _open(self._datfile, 'r')