fix user_id / user confusion

1 files changed, 1 insertions, 1 deletions

diff --git a/synapse/types.py b/synapse/types.py

index 46be4a071d..00e6e1c369 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -238,7 +238,7 @@ def strip_invalid_mxid_characters(localpart):
     Returns:
         localpart (basestring): the localpart having been stripped
     """
-    return filter(lambda c: c not in mxid_localpart_allowed_characters, localpart)
+    return filter(lambda c: c in mxid_localpart_allowed_characters, localpart)
 
 
 class StreamToken(