diff --git a/lib/storage/WebStorage.js b/lib/storage/WebStorage.js
index 6b4889f90..b3e2c11e2 100644
--- a/lib/storage/WebStorage.js
+++ b/lib/storage/WebStorage.js
@@ -40,6 +40,9 @@ const webStorage = {
         this.removeItems = keys => Storage.removeItems(keys)
             .then(() => raiseStorageSyncManyKeysEvent(keys));
 
+        this.mergeItem = (key, batchedChanges, modifiedData) => Storage.mergeItem(key, batchedChanges, modifiedData)
+            .then(() => raiseStorageSyncEvent(key));
+
         // If we just call Storage.clear other tabs will have no idea which keys were available previously
         // so that they can call keysChanged for them. That's why we iterate over every key and raise a storage sync
         // event for each one