diff --git a/lib/index.js b/lib/index.js
index 5298128..067c1e8 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -38,12 +38,12 @@ function addWatchTask(taker, name, description) {
     return task.hasOwnProperty('_watch') && task._watch;
   });
   // Define the watch function.
-  let watch = () => {
+  let watch = (cb) => {
     for (let watchableName of watchables) {
       const watchableTask = taker.task(watchableName);
       taker.watch(watchableTask.unwrap()._watch, watchableTask);
     }
-    return Promise.resolve();
+    cb();
   };
   // Push an initial run of each watchable task onto the beginning.
   if (watchables.length > 0) {