diff --git a/lib/pushprocessor.js b/lib/pushprocessor.js
index 173046109..5104420d5 100644
--- a/lib/pushprocessor.js
+++ b/lib/pushprocessor.js
@@ -125,7 +125,7 @@ function PushProcessor(client) {
         var room = client.getRoom(ev.room_id);
         if (!room || !room.currentState || !room.currentState.members) { return false; }
 
-        var memberCount = Object.keys(room.currentState.members).filter((m) => {
+        var memberCount = Object.keys(room.currentState.members).filter(function(m) {
             return room.currentState.members[m].membership == 'join';
         }).length;