Merge pull request #583 from 0xProject/bug/contracts/erc721-encoded-pad

ERC721Proxy Pad to 32 if asset ids are small

1 files changed, 2 insertions, 1 deletions

diff --git a/packages/contracts/src/utils/asset_proxy_utils.ts b/packages/contracts/src/utils/asset_proxy_utils.ts
index 1a7a312dd..dc31c3497 100644
--- a/packages/contracts/src/utils/asset_proxy_utils.ts
+++ b/packages/contracts/src/utils/asset_proxy_utils.ts
@@ -18,7 +18,8 @@ export const assetProxyUtils = {
     encodeUint256(value: BigNumber): Buffer {
         const formattedValue = new BN(value.toString(10));
         const encodedValue = ethUtil.toBuffer(formattedValue);
-        return encodedValue;
+        const paddedValue = ethUtil.setLengthLeft(encodedValue, 32);
+        return paddedValue;
     },
     encodeERC20ProxyData(tokenAddress: string): string {
         const encodedAssetProxyId = assetProxyUtils.encodeAssetProxyId(AssetProxyId.ERC20);