diff --git a/lib/modules/storage/task.js b/lib/modules/storage/task.js
index 3b2ced7d..39ad9622 100644
--- a/lib/modules/storage/task.js
+++ b/lib/modules/storage/task.js
@@ -42,7 +42,7 @@ export default class StorageTask {
   ref: StorageReference
   storage: StorageReference.storage
   path: StorageReference.path
-  then: Promise<*>
+  then: () => Promise<*>
   catch: () => Promise<*>
 
   constructor(type: typeof UPLOAD_TASK | typeof DOWNLOAD_TASK, promise: Promise<*>, storageRef: StorageReference) {
@@ -52,7 +52,7 @@ export default class StorageTask {
     this.path = storageRef.path;
 
     // 'proxy' original promise
-    this.then = promise.then(this._interceptSnapshotEvent);
+    this.then = promise.then.bind(promise);
     this.catch = promise.catch.bind(promise);
   }