diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index d65a7893d..3e552b6c4 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -323,7 +323,7 @@ class FederationSendLeaveServlet(BaseFederationServlet):
 
 
 class FederationEventAuthServlet(BaseFederationServlet):
-    PATH = "/event_auth(?P<context>[^/]*)/(?P<event_id>[^/]*)"
+    PATH = "/event_auth/(?P<context>[^/]*)/(?P<event_id>[^/]*)"
 
     def on_GET(self, origin, content, query, context, event_id):
         return self.handler.on_event_auth(origin, context, event_id)