diff --git a/src/interfaces/SpokePool.ts b/src/interfaces/SpokePool.ts
index 37b228452..7d2f41037 100644
--- a/src/interfaces/SpokePool.ts
+++ b/src/interfaces/SpokePool.ts
@@ -19,6 +19,7 @@ export interface RelayData {
   fillDeadline: number;
   exclusiveRelayer: string;
   exclusivityDeadline: number;
+  _hash?: Record<number, string>;
 }
 
 export interface Deposit extends RelayData {
diff --git a/src/utils/SpokeUtils.ts b/src/utils/SpokeUtils.ts
index 554b777f0..863eb0c02 100644
--- a/src/utils/SpokeUtils.ts
+++ b/src/utils/SpokeUtils.ts
@@ -216,7 +216,9 @@ export async function getDepositIdAtBlock(contract: Contract, blockTag: number):
  * @returns The corresponding RelayData hash.
  */
 export function getRelayDataHash(relayData: RelayData, destinationChainId: number): string {
-  return ethersUtils.keccak256(
+  relayData._hash ??= {};
+
+  return (relayData._hash[destinationChainId] ??= ethersUtils.keccak256(
     ethersUtils.defaultAbiCoder.encode(
       [
         "tuple(" +
@@ -237,7 +239,7 @@ export function getRelayDataHash(relayData: RelayData, destinationChainId: numbe
       ],
       [relayData, destinationChainId]
     )
-  );
+  ));
 }
 
 export function getRelayHashFromEvent(e: Deposit | Fill | SlowFillRequest): string {
diff --git a/test/SpokePoolClient.ValidateFill.ts b/test/SpokePoolClient.ValidateFill.ts
index fc5e6fb35..5026c7a6c 100644
--- a/test/SpokePoolClient.ValidateFill.ts
+++ b/test/SpokePoolClient.ValidateFill.ts
@@ -216,7 +216,7 @@ describe("SpokePoolClient: Fill Validation", function () {
     await spokePoolClient1.update();
 
     expect(spokePoolClient1.getDepositForFill(fill))
-      .excludingEvery(["realizedLpFeePct", "quoteBlockNumber"])
+      .excludingEvery(["realizedLpFeePct", "quoteBlockNumber", "_hash"])
       .to.deep.equal(deposit);
   });
 
@@ -631,7 +631,7 @@ describe("SpokePoolClient: Fill Validation", function () {
     expect(fill_2.relayExecutionInfo.fillType === FillType.FastFill).to.be.true;
 
     expect(spokePoolClient1.getDepositForFill(fill_1))
-      .excludingEvery(["quoteBlockNumber", "realizedLpFeePct"])
+      .excludingEvery(["quoteBlockNumber", "realizedLpFeePct", "_hash"])
       .to.deep.equal(deposit_1);
     expect(spokePoolClient1.getDepositForFill(fill_2)).to.equal(undefined);
 
@@ -652,22 +652,24 @@ describe("SpokePoolClient: Fill Validation", function () {
 
     expect(validateFillForDeposit(validFill, deposit_2)).to.be.true;
 
+    const _hash = undefined;
+
     // Invalid input amount.
-    expect(validateFillForDeposit({ ...validFill, inputAmount: toBNWei(1337) }, deposit_2)).to.be.false;
+    expect(validateFillForDeposit({ ...validFill, inputAmount: toBNWei(1337), _hash }, deposit_2)).to.be.false;
 
     // Changed the output token.
-    expect(validateFillForDeposit(validFill, { ...deposit_2, outputToken: owner.address })).to.be.false;
+    expect(validateFillForDeposit(validFill, { ...deposit_2, outputToken: owner.address, _hash })).to.be.false;
 
     // Changed the output amount.
-    expect(validateFillForDeposit({ ...validFill, outputAmount: toBNWei(1337) }, deposit_2)).to.be.false;
+    expect(validateFillForDeposit({ ...validFill, outputAmount: toBNWei(1337), _hash }, deposit_2)).to.be.false;
 
     // Invalid depositId.
-    expect(validateFillForDeposit({ ...validFill, depositId: 1337 }, deposit_2)).to.be.false;
+    expect(validateFillForDeposit({ ...validFill, depositId: 1337, _hash }, deposit_2)).to.be.false;
 
     // Changed the depositor.
-    expect(validateFillForDeposit({ ...validFill, depositor: relayer.address }, deposit_2)).to.be.false;
+    expect(validateFillForDeposit({ ...validFill, depositor: relayer.address, _hash }, deposit_2)).to.be.false;
 
     // Changed the recipient.
-    expect(validateFillForDeposit({ ...validFill, recipient: relayer.address }, deposit_2)).to.be.false;
+    expect(validateFillForDeposit({ ...validFill, recipient: relayer.address, _hash }, deposit_2)).to.be.false;
   });
 });
diff --git a/test/SpokePoolClient.v3Events.ts b/test/SpokePoolClient.v3Events.ts
index 17c5edb79..3ea796b5e 100644
--- a/test/SpokePoolClient.v3Events.ts
+++ b/test/SpokePoolClient.v3Events.ts
@@ -209,9 +209,9 @@ describe("SpokePoolClient: Event Filtering", function () {
       // The SpokePoolClient appends destinationChainId, so check for it specifically.
       expect(slowFillRequest?.destinationChainId).to.not.be.undefined;
       expect(slowFillRequest?.destinationChainId).to.equal(destinationChainId);
-      Object.entries(relayData).forEach(
-        ([k, v]) => expect(isDefined(v)).to.equal(true) && expect(slowFillRequest?.[k]).to.equal(v)
-      );
+      Object.entries(relayData)
+        .filter(([k]) => k !== "_hash")
+        .forEach(([k, v]) => expect(isDefined(v)).to.equal(true) && expect(slowFillRequest?.[k]).to.equal(v));
     });
   });