1 files changed, 4 insertions, 2 deletions
diff --git a/packages/types/src/index.ts b/packages/types/src/index.ts
index 6bc966ba1..ff4c6f0cc 100644
--- a/packages/types/src/index.ts
+++ b/packages/types/src/index.ts
@@ -158,16 +158,18 @@ export enum AssetProxyId {
 }
 
 export interface ERC20AssetData {
-    assetProxyId: string;
+    assetProxyId: AssetProxyId.ERC20;
     tokenAddress: string;
 }
 
 export interface ERC721AssetData {
-    assetProxyId: string;
+    assetProxyId: AssetProxyId.ERC721;
     tokenAddress: string;
     tokenId: BigNumber;
 }
 
+export type AssetData = ERC20AssetData | ERC721AssetData;
+
 // TODO: DRY. These should be extracted from contract code.
 export enum RevertReason {
     OrderUnfillable = 'ORDER_UNFILLABLE',