diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index 394e6b380..bd57d11dc 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -143,9 +143,9 @@ class ThreepidRestServlet(RestServlet):
         )
 
         if 'bind' in body and body['bind']:
-            logger.debug("Binding emails %s to %s" % (
+            logger.debug("Binding emails %s to %s",
                 threepid, auth_user.to_string()
-            ))
+            )
             yield self.identity_handler.bind_threepid(
                 threePidCreds, auth_user.to_string()
             )