diff --git a/src/lib/trades.spec.ts b/src/lib/trades.spec.ts
index 29d324ed..566e76ee 100644
--- a/src/lib/trades.spec.ts
+++ b/src/lib/trades.spec.ts
@@ -166,8 +166,8 @@ describe('when getting the trade signature', () => {
       domain = {
         name: offchainMarketplaceContract.name,
         version: offchainMarketplaceContract.version,
-        salt: SALT,
-        verifyingContract: offchainMarketplaceContract.address
+        verifyingContract: offchainMarketplaceContract.address,
+        salt: SALT
       }
 
       values = {
@@ -182,7 +182,7 @@ describe('when getting the trade signature', () => {
           externalChecks: trade.checks.externalChecks?.map(externalCheck => ({
             contractAddress: externalCheck.contractAddress,
             selector: externalCheck.selector,
-            value: externalCheck.value,
+            value: '0x',
             required: externalCheck.required
           }))
         },
@@ -190,13 +190,13 @@ describe('when getting the trade signature', () => {
           assetType: asset.assetType,
           contractAddress: asset.contractAddress,
           value: getValueForTradeAsset(asset),
-          extra: ethers.utils.hexlify(ethers.utils.toUtf8Bytes(asset.extra))
+          extra: '0x'
         })),
         received: trade.received.map(asset => ({
           assetType: asset.assetType,
           contractAddress: asset.contractAddress,
           value: getValueForTradeAsset(asset),
-          extra: ethers.utils.hexlify(ethers.utils.toUtf8Bytes(asset.extra)),
+          extra: '0x',
           beneficiary: asset.beneficiary
         }))
       }
@@ -274,14 +274,14 @@ describe('when getting the trade to accept', () => {
         assetType: asset.assetType,
         contractAddress: asset.contractAddress,
         value: getValueForTradeAsset(asset),
-        extra: ethers.utils.hexlify(ethers.utils.toUtf8Bytes(asset.extra)),
+        extra: '0x',
         beneficiary: beneficiaryAddress
       })),
       received: trade.received.map(asset => ({
         assetType: asset.assetType,
         contractAddress: asset.contractAddress,
         value: getValueForTradeAsset(asset),
-        extra: ethers.utils.hexlify(ethers.utils.toUtf8Bytes(asset.extra)),
+        extra: '0x',
         beneficiary: asset.beneficiary
       }))
     })
diff --git a/src/lib/trades.ts b/src/lib/trades.ts
index 094e3ff9..57b22a81 100644
--- a/src/lib/trades.ts
+++ b/src/lib/trades.ts
@@ -97,9 +97,8 @@ export function generateTradeValues(trade: Omit<TradeCreation, 'signature'>) {
       externalChecks: trade.checks.externalChecks?.map(externalCheck => ({
         contractAddress: externalCheck.contractAddress,
         selector: externalCheck.selector,
-        value: ethers.utils.hexlify(
-          ethers.utils.toUtf8Bytes(externalCheck.value)
-        ),
+        // '0x' is the default value for value bytes (0 bytes)
+        value: externalCheck.value ? externalCheck.value : '0x',
         required: externalCheck.required
       }))
     },
@@ -107,13 +106,15 @@ export function generateTradeValues(trade: Omit<TradeCreation, 'signature'>) {
       assetType: asset.assetType,
       contractAddress: asset.contractAddress,
       value: getValueForTradeAsset(asset),
-      extra: ethers.utils.hexlify(ethers.utils.toUtf8Bytes(asset.extra))
+      // '0x' is the default value for value bytes (0 bytes)
+      extra: asset.extra ? asset.extra : '0x'
     })),
     received: trade.received.map(asset => ({
       assetType: asset.assetType,
       contractAddress: asset.contractAddress,
       value: getValueForTradeAsset(asset),
-      extra: ethers.utils.hexlify(ethers.utils.toUtf8Bytes(asset.extra)),
+      // '0x' is the default value for value bytes (0 bytes)
+      extra: asset.extra ? asset.extra : '0x',
       beneficiary: asset.beneficiary
     }))
   }