1 files changed, 6 insertions, 4 deletions
diff --git a/synapse/http/server.py b/synapse/http/server.py
index b17b190ee5..b82196fd5e 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -18,6 +18,7 @@ from synapse.api.errors import (
     cs_exception, SynapseError, CodeMessageException, UnrecognizedRequestError, Codes
 )
 from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
+from synapse.util.caches import intern_dict
 import synapse.metrics
 import synapse.events
 
@@ -229,11 +230,12 @@ class JsonResource(HttpServer, resource.Resource):
             else:
                 servlet_classname = "%r" % callback
 
-            args = [
-                urllib.unquote(u).decode("UTF-8") if u else u for u in m.groups()
-            ]
+            kwargs = intern_dict({
+                name: urllib.unquote(value).decode("UTF-8") if value else value
+                for name, value in m.groupdict().items()
+            })
 
-            callback_return = yield callback(request, *args)
+            callback_return = yield callback(request, **kwargs)
             if callback_return is not None:
                 code, response = callback_return
                 self._send_response(request, code, response)