diff --git a/lib/models/event.js b/lib/models/event.js
index 859c2b488..83bf207c3 100644
--- a/lib/models/event.js
+++ b/lib/models/event.js
@@ -234,7 +234,8 @@ module.exports.MatrixEvent.prototype = {
     },
 
     /**
-     * Returns the curve25519 key that sent this event
+     * The curve25519 key that sent this event
+     * @return {string}
      */
     getSenderKey: function() {
         return this.getKeysProved().curve25519 || null;