diff --git a/.gitignore b/.gitignore
index 93f1361..160cf78 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 node_modules
 npm-debug.log
+.idea
+yarn.lock
diff --git a/index.js b/index.js
index 74af191..64e4a40 100644
--- a/index.js
+++ b/index.js
@@ -1,8 +1,8 @@
 'use strict'
 
-module.exports = function promiseWaterfall (callbacks) {
+module.exports = function promiseWaterfall (callbacks, initialArgs) {
   // Don't assume we're running in an environment with promises
   return callbacks.reduce(function (accumulator, callback) {
     return accumulator.then(callback)
-  }, Promise.resolve())
+  }, Promise.resolve(initialArgs))
 }
diff --git a/test.js b/test.js
index ad186e2..692a60c 100644
--- a/test.js
+++ b/test.js
@@ -34,6 +34,18 @@ test('run array of promises sequentially', function (t) {
     })
 })
 
+test('run array of promises sequentially with an initialization parameter', function (t) {
+  t.plan(1)
+
+  return promiseWaterfall([
+    addOne,
+    addTwo
+  ], 10)
+    .then(function (sum) {
+      t.equals(sum, 13)
+    })
+})
+
 test('run array consisting of zero promises', function (t) {
   t.plan(1)