diff --git a/packages/0x.js/CHANGELOG.md b/packages/0x.js/CHANGELOG.md
index 3b90691a78..56a1e1ab0d 100644
--- a/packages/0x.js/CHANGELOG.md
+++ b/packages/0x.js/CHANGELOG.md
@@ -2,7 +2,7 @@
 
 Pending
 ------------------------
-    * Subscribe to ZRX Token Transfer and Approval events when maker token is different
+    * In OrderWatcher subscribe to ZRX Token Transfer and Approval events when maker token is different (#225)
 
 v0.25.1 - _November 13, 2017_
 ------------------------
diff --git a/packages/0x.js/src/order_watcher/order_state_watcher.ts b/packages/0x.js/src/order_watcher/order_state_watcher.ts
index 4215248085..9f756dbc32 100644
--- a/packages/0x.js/src/order_watcher/order_state_watcher.ts
+++ b/packages/0x.js/src/order_watcher/order_state_watcher.ts
@@ -213,7 +213,7 @@ export class OrderStateWatcher {
             await this._callbackIfExistsAsync(orderState);
         }
     }
-    private async addToDependentOrderHashes(signedOrder: SignedOrder, orderHash: string) {
+    private async addToDependentOrderHashes(signedOrder: SignedOrder, orderHash: string): Promise<void> {
         if (_.isUndefined(this._dependentOrderHashes[signedOrder.maker])) {
             this._dependentOrderHashes[signedOrder.maker] = {};
         }