Check isETHAddressHex before lowercase

Flip the check so assertion happens before lowercase

1 files changed, 1 insertions, 1 deletions

diff --git a/packages/0x.js/src/contract_wrappers/token_transfer_proxy_wrapper.ts b/packages/0x.js/src/contract_wrappers/token_transfer_proxy_wrapper.ts
index 41afd2f67..f0cbf364d 100644
--- a/packages/0x.js/src/contract_wrappers/token_transfer_proxy_wrapper.ts
+++ b/packages/0x.js/src/contract_wrappers/token_transfer_proxy_wrapper.ts
@@ -23,8 +23,8 @@ export class TokenTransferProxyWrapper extends ContractWrapper {
      * @return  Whether the exchangeContractAddress is authorized.
      */
     public async isAuthorizedAsync(exchangeContractAddress: string): Promise<boolean> {
+        assert.isETHAddressHex('exchangeContractAddress', exchangeContractAddress);
         const normalizedExchangeContractAddress = exchangeContractAddress.toLowerCase();
-        assert.isETHAddressHex('exchangeContractAddress', normalizedExchangeContractAddress);
         const tokenTransferProxyContractInstance = await this._getTokenTransferProxyContractAsync();
         const isAuthorized = await tokenTransferProxyContractInstance.authorized.callAsync(
             normalizedExchangeContractAddress,