diff --git a/tools/mkssldef.py b/tools/mkssldef.py
index 4768d1ff0ff..43e01b4bf70 100755
--- a/tools/mkssldef.py
+++ b/tools/mkssldef.py
@@ -26,7 +26,7 @@ if __name__ == '__main__':
 
   for filename in filenames:
     for line in open(filename).readlines():
-      name, _, _, meta, _ = re.split('\s+', line)
+      name, _, _, meta, _ = re.split(r'\s+', line)
       if any(p.match(name) for p in excludes): continue
       meta = meta.split(':')
       assert meta[0] in ('EXIST', 'NOEXIST')