diff --git a/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/membership_table.go b/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/membership_table.go
index c8a4f9637..07d1fd293 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/membership_table.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/auth/storage/accounts/membership_table.go
@@ -27,11 +27,9 @@ CREATE TABLE IF NOT EXISTS memberships (
     -- The room this user is a member of
     room_id TEXT NOT NULL,
 
+	-- A user can only be member of a room once
 	PRIMARY KEY (localpart, room_id)
 );
-
--- A user can only be member of a room once
-CREATE UNIQUE INDEX IF NOT EXISTS localpart_id_idx ON memberships(localpart, room_id);
 `
 
 const insertMembershipSQL = "" +