diff --git a/lib/cascade-update.js b/lib/cascade-update.js
index 38a532c..2ae9128 100644
--- a/lib/cascade-update.js
+++ b/lib/cascade-update.js
@@ -2,6 +2,7 @@
 
 const debug = require('debug')('loopback:mixins:cascade-update')
 const _ = require('lodash')
+const Promise = require('bluebird')
 
 module.exports = function cascadeUpdateMixin(Model, options) {
 
diff --git a/package.json b/package.json
index f5c510c..89d2b00 100644
--- a/package.json
+++ b/package.json
@@ -57,6 +57,7 @@
     "validate-commit-msg": "2.12.2"
   },
   "dependencies": {
+    "bluebird": "^3.5.0",
     "debug": "2.6.8",
     "lodash": "^4.17.4"
   },