diff --git a/lib/mock.js b/lib/mock.js
index bf4fae0..235cbae 100644
--- a/lib/mock.js
+++ b/lib/mock.js
@@ -106,6 +106,9 @@ function createPromisable (wrapped) {
 				send: function (cb) {
 					args.push(cb)
 					this._returned = wrapped.apply(self, args)
+				},
+				on: function (event, cb) {
+					cb()
 				}
 			}
 		}