diff --git a/gluon/rewrite.py b/gluon/rewrite.py
index 1939695c..40fb9adb 100644
--- a/gluon/rewrite.py
+++ b/gluon/rewrite.py
@@ -81,7 +81,7 @@ def _router_default():
         #  pathological backtracking from nested patterns.
         #
         file_match = r'([-+=@$%\w]|(?<=[-+=@$%\w])[./])*$', # legal static subpath
-        args_match=r'([\w@ -]|(?<=[\w@ -])[.=])*$',         # legal arg in args
+        args_match=r'([\w@ -=]|(?<=[\w@ -=])[.])*$',         # legal arg in args
     )
     return router