1 files changed, 1 insertions, 1 deletions
diff --git a/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts b/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts
index b1d5a0ccc..238009759 100644
--- a/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/ether_token_wrapper.ts
@@ -27,7 +27,7 @@ import {TokenWrapper} from './token_wrapper';
  * The caller can convert ETH into the equivalent number of wrapped ETH ERC20 tokens and back.
  */
 export class EtherTokenWrapper extends ContractWrapper {
-    private _etherTokenContractsByAddress: {[address: string]: EtherTokenContract};
+    private _etherTokenContractsByAddress: {[address: string]: EtherTokenContract} = {};
     private _tokenWrapper: TokenWrapper;
     constructor(web3Wrapper: Web3Wrapper, networkId: number, abiDecoder: AbiDecoder, tokenWrapper: TokenWrapper) {
         super(web3Wrapper, networkId, abiDecoder);