diff --git a/.eslintignore b/.eslintignore
index dfd3a0917..8a2103827 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -4,3 +4,5 @@ cache
 coverage*
 gasReporterOutput.json
 typechain
+artifacts-zk
+cache-zk
diff --git a/.npmignore b/.npmignore
index c4ff6d397..f6ef6a5b9 100644
--- a/.npmignore
+++ b/.npmignore
@@ -1,2 +1,3 @@
 hardhat.config.ts
 cache
+cache-zk
\ No newline at end of file
diff --git a/.prettierignore b/.prettierignore
index 77d708c34..59766e79e 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -5,3 +5,5 @@ coverage*
 gasReporterOutput.json
 typechain
 dist
+artifacts-zk
+cache-zk
diff --git a/contracts/SpokePool.sol b/contracts/SpokePool.sol
index 79488dee6..01660c33b 100644
--- a/contracts/SpokePool.sol
+++ b/contracts/SpokePool.sol
@@ -460,7 +460,7 @@ abstract contract SpokePool is
         bytes memory updatedMessage,
         bytes memory depositorSignature
     ) public override nonReentrant {
-        require(updatedRelayerFeePct < 0.5e18, "invalid relayer fee");
+        require(SignedMath.abs(updatedRelayerFeePct) < 0.5e18, "Invalid relayer fee");
 
         _verifyUpdateDepositMessage(
             depositor,
diff --git a/test/SpokePool.Relay.ts b/test/SpokePool.Relay.ts
index 2f376555b..920ea35ef 100644
--- a/test/SpokePool.Relay.ts
+++ b/test/SpokePool.Relay.ts
@@ -303,7 +303,7 @@ async function testUpdatedFeeSignaling(depositorAddress: string) {
     updatedMessage
   );
 
-  // Cannot set new relayer fee pct >= 50%
+  // Cannot set new relayer fee pct >= 50% or <= -50%
   await expect(
     spokePool
       .connect(relayer)
@@ -315,7 +315,19 @@ async function testUpdatedFeeSignaling(depositorAddress: string) {
         updatedMessage,
         signature
       )
-  ).to.be.revertedWith("invalid relayer fee");
+  ).to.be.revertedWith("Invalid relayer fee");
+  await expect(
+    spokePool
+      .connect(relayer)
+      .speedUpDeposit(
+        depositorAddress,
+        toWei("0.5").mul(-1),
+        consts.firstDepositId,
+        updatedRecipient,
+        updatedMessage,
+        signature
+      )
+  ).to.be.revertedWith("Invalid relayer fee");
 
   await expect(
     spokePool