1 files changed, 1 insertions, 0 deletions
diff --git a/packages/contract-wrappers/src/contract_wrappers/erc20_token_wrapper.ts b/packages/contract-wrappers/src/contract_wrappers/erc20_token_wrapper.ts
index a6e5d8765..f393e4ed1 100644
--- a/packages/contract-wrappers/src/contract_wrappers/erc20_token_wrapper.ts
+++ b/packages/contract-wrappers/src/contract_wrappers/erc20_token_wrapper.ts
@@ -379,6 +379,7 @@ export class ERC20TokenWrapper extends ContractWrapper {
      * @param   subscriptionToken Subscription token returned by `subscribe()`
      */
     public unsubscribe(subscriptionToken: string): void {
+        assert.isValidSubscriptionToken('subscriptionToken', subscriptionToken);
         this._unsubscribe(subscriptionToken);
     }
     /**