diff --git a/packages/0x.js/test/token_wrapper_test.ts b/packages/0x.js/test/token_wrapper_test.ts
index 07276877dc..c32c528e61 100644
--- a/packages/0x.js/test/token_wrapper_test.ts
+++ b/packages/0x.js/test/token_wrapper_test.ts
@@ -363,6 +363,7 @@ describe('TokenWrapper', () => {
                     expect(logEvent).to.not.be.undefined();
                     expect(logEvent.logIndex).to.be.equal(0);
                     expect(logEvent.transactionIndex).to.be.equal(0);
+                    expect(logEvent.blockNumber).to.be.instanceOf(Number);
                     const args = logEvent.args;
                     expect(args._from).to.be.equal(coinbase);
                     expect(args._to).to.be.equal(addressWithoutFunds);