diff --git a/externs/cosmopolite.js b/externs/cosmopolite.js
index a6be300..bf8e5db 100644
--- a/externs/cosmopolite.js
+++ b/externs/cosmopolite.js
@@ -61,6 +61,14 @@ function Cosmopolite(opt_urlPrefix, opt_namespace, opt_trackingID) {}
 Cosmopolite.prototype.shutdown = function() {};
 
 
+/**
+ * @see https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener
+ * @param {string} type
+ * @param {function(Event)} listener
+ */
+Cosmopolite.prototype.addEventListener = function(type, listener) {};
+
+
 /**
  * @see https://www.cosmopolite.org/reference#connected
  * @return {boolean}