diff --git a/conf/config.yaml b/conf/config.yaml
index 68d4ccc..780f69c 100644
--- a/conf/config.yaml
+++ b/conf/config.yaml
@@ -113,7 +113,7 @@ manhole:
 bridge:
     # Localpart template of MXIDs for Facebook users.
     # {userid} is replaced with the user ID of the Facebook user.
-    username_template: "facebook_{userid}"
+    username_template: "fb_{userid}"
     # Displayname template for Facebook users.
     # {displayname} is replaced with the display name of the Facebook user
     #               as defined below in displayname_preference.