diff --git a/ryu/app/wsgi.py b/ryu/app/wsgi.py
index <HASH>..<HASH> 100644
--- a/ryu/app/wsgi.py
+++ b/ryu/app/wsgi.py
@@ -225,23 +225,15 @@ class WSGIApplication(object):
         self.registory = {}
         self._wsmanager = WebSocketManager()
         super(WSGIApplication, self).__init__()
-        # XXX: Switch how to call the API of Routes for every version
-        match_argspec = inspect.getargspec(self.mapper.match)
-        if 'environ' in match_argspec.args:
-            # New API
-            self._match = self._match_with_environ
-        else:
-            # Old API
-            self._match = self._match_with_path_info
-
-    def _match_with_environ(self, req):
-        match = self.mapper.match(environ=req.environ)
-        return match
-
-    def _match_with_path_info(self, req):
-        self.mapper.environ = req.environ
-        match = self.mapper.match(req.path_info)
-        return match
+
+    def _match(self, req):
+        # Note: Invoke the new API, first. If the arguments unmatched,
+        # invoke the old API.
+        try:
+            return self.mapper.match(environ=req.environ)
+        except TypeError:
+            self.mapper.environ = req.environ
+            return self.mapper.match(req.path_info)
 
     @wsgify_hack
     def __call__(self, req, start_response):
wsgi: Avoid using inspect.getargspec

Officially, "inspect.getargspec" is obsoleted in Python <I>,
this patch fixes to avoid using this function.