diff --git a/source/delegate/contracts/Delegate.sol b/source/delegate/contracts/Delegate.sol
index 42e3d35e8..80a2022f1 100644
--- a/source/delegate/contracts/Delegate.sol
+++ b/source/delegate/contracts/Delegate.sol
@@ -133,22 +133,21 @@ contract Delegate is IDelegate, Ownable {
     bytes32 _s
   ) external {
     Rule storage rule = rules[_senderWallet][_senderToken][_signerToken];
-    // Ensure the signer amount is valid
-    if (
-      _signerAmount <
-      (rule.signerAmount * (rule.senderAmount - rule.senderFilledAmount)) /
-        rule.senderAmount
-    ) {
-      revert SignerAmountInvalid();
-    }
-    // Ensure the rule has not expired
-    if (rule.expiry < block.timestamp) revert RuleExpired();
+    // Ensure the expiry is not passed
+    if (rule.expiry <= block.timestamp) revert RuleExpiredOrDoesNotExist();
 
     // Ensure the sender amount is valid
     if (_senderAmount > (rule.senderAmount - rule.senderFilledAmount)) {
       revert SenderAmountInvalid();
     }
 
+    // Ensure the signer amount is valid
+    if (
+      rule.signerAmount * _senderAmount != rule.senderAmount * _signerAmount
+    ) {
+      revert SignerAmountInvalid();
+    }
+
     // Transfer the sender token to this contract
     SafeTransferLib.safeTransferFrom(
       _senderToken,
diff --git a/source/delegate/contracts/interfaces/IDelegate.sol b/source/delegate/contracts/interfaces/IDelegate.sol
index 7f1cb0c3f..bd0412ba4 100644
--- a/source/delegate/contracts/interfaces/IDelegate.sol
+++ b/source/delegate/contracts/interfaces/IDelegate.sol
@@ -33,7 +33,7 @@ interface IDelegate {
   );
 
   error AddressInvalid();
-  error RuleExpired();
+  error RuleExpiredOrDoesNotExist();
   error SenderAmountInvalid();
   error SignerAmountInvalid();
   error SenderInvalid();
diff --git a/source/delegate/test/Delegate.js b/source/delegate/test/Delegate.js
index d2a8ea79a..c80d4dcda 100644
--- a/source/delegate/test/Delegate.js
+++ b/source/delegate/test/Delegate.js
@@ -13,7 +13,7 @@ const {
 } = require('@airswap/utils')
 const CHAIN_ID = 31337
 const DEFAULT_BALANCE = '100000'
-const DEFAULT_SENDER_AMOUNT = '10000'
+const DEFAULT_SENDER_AMOUNT = '5000'
 const DEFAULT_SIGNER_AMOUNT = '10000'
 const PROTOCOL_FEE = '5'
 const REBATE_SCALE = '10'
@@ -456,13 +456,41 @@ describe('Delegate Unit', () => {
         .withArgs(delegate.address)
         .returns(DEFAULT_SIGNER_AMOUNT)
 
-      await expect(delegate.connect(signer).swap(sender.address, ...order)).to
-        .be.reverted
+      await expect(
+        delegate.connect(signer).swap(sender.address, ...order)
+      ).to.be.revertedWith('RuleExpiredOrDoesNotExist')
     })
 
-    it('fails to swap with insufficient remaining sender amount on Rule', async () => {
+    it('fails to swap with a rule expired', async () => {
+      await delegate
+        .connect(sender)
+        .setRule(
+          sender.address,
+          senderToken.address,
+          DEFAULT_SENDER_AMOUNT,
+          signerToken.address,
+          DEFAULT_SIGNER_AMOUNT,
+          Math.round(Date.now() / 1000) - 10
+        )
+
+      const order = await createSignedOrderERC20({}, signer)
+
+      await setUpAllowances(
+        sender.address,
+        DEFAULT_SENDER_AMOUNT,
+        signer.address,
+        DEFAULT_SIGNER_AMOUNT + PROTOCOL_FEE
+      )
+      await setUpBalances(signer.address, sender.address)
+
+      await expect(
+        delegate.connect(signer).swap(sender.address, ...order)
+      ).to.be.revertedWith('RuleExpiredOrDoesNotExist')
+    })
+
+    it('fails to swap with sender amount above rule sender amount', async () => {
       await senderToken.mock.approve
-        .withArgs(delegate.address, DEFAULT_SENDER_AMOUNT - 1)
+        .withArgs(delegate.address, DEFAULT_SENDER_AMOUNT / 2)
         .returns(true)
 
       await delegate
@@ -470,9 +498,9 @@ describe('Delegate Unit', () => {
         .setRule(
           sender.address,
           senderToken.address,
-          DEFAULT_SENDER_AMOUNT - 1,
+          DEFAULT_SENDER_AMOUNT / 2,
           signerToken.address,
-          DEFAULT_SIGNER_AMOUNT,
+          DEFAULT_SIGNER_AMOUNT / 2,
           RULE_EXPIRY
         )
 
@@ -488,16 +516,16 @@ describe('Delegate Unit', () => {
 
       await signerToken.mock.balanceOf
         .withArgs(signer.address)
-        .returns(DEFAULT_SIGNER_AMOUNT - 1)
+        .returns(DEFAULT_SIGNER_AMOUNT)
 
       await expect(
         delegate.connect(signer).swap(sender.address, ...order)
       ).to.be.revertedWith('SenderAmountInvalid')
     })
 
-    it('fails to swap with insufficient signer amount on Rule', async () => {
+    it('fails to swap with sender amount above remaining rule sender amount', async () => {
       await senderToken.mock.approve
-        .withArgs(delegate.address, DEFAULT_SENDER_AMOUNT - 1)
+        .withArgs(delegate.address, DEFAULT_SENDER_AMOUNT / 2)
         .returns(true)
 
       await delegate
@@ -511,12 +539,7 @@ describe('Delegate Unit', () => {
           RULE_EXPIRY
         )
 
-      const order = await createSignedOrderERC20(
-        {
-          signerAmount: DEFAULT_SIGNER_AMOUNT - 1,
-        },
-        signer
-      )
+      const order = await createSignedOrderERC20({}, signer)
 
       await setUpAllowances(
         sender.address,
@@ -528,14 +551,24 @@ describe('Delegate Unit', () => {
 
       await signerToken.mock.balanceOf
         .withArgs(signer.address)
-        .returns(DEFAULT_SIGNER_AMOUNT - 1)
+        .returns(DEFAULT_SIGNER_AMOUNT)
 
       await expect(
         delegate.connect(signer).swap(sender.address, ...order)
-      ).to.be.revertedWith('SignerAmountInvalid')
+      ).to.emit(delegate, 'DelegateSwap')
+
+      const order2 = await createSignedOrderERC20({}, signer)
+
+      await expect(
+        delegate.connect(signer).swap(sender.address, ...order2)
+      ).to.be.revertedWith('SenderAmountInvalid')
     })
 
-    it('fails to swap with a rule expired', async () => {
+    it('fails to swap with insufficient signer amount on Rule', async () => {
+      await senderToken.mock.approve
+        .withArgs(delegate.address, DEFAULT_SENDER_AMOUNT - 1)
+        .returns(true)
+
       await delegate
         .connect(sender)
         .setRule(
@@ -544,10 +577,16 @@ describe('Delegate Unit', () => {
           DEFAULT_SENDER_AMOUNT,
           signerToken.address,
           DEFAULT_SIGNER_AMOUNT,
-          0
+          RULE_EXPIRY
         )
 
-      const order = await createSignedOrderERC20({}, signer)
+      const order = await createSignedOrderERC20(
+        {
+          senderAmount: DEFAULT_SENDER_AMOUNT,
+          signerAmount: DEFAULT_SIGNER_AMOUNT / 4,
+        },
+        signer
+      )
 
       await setUpAllowances(
         sender.address,
@@ -557,9 +596,13 @@ describe('Delegate Unit', () => {
       )
       await setUpBalances(signer.address, sender.address)
 
+      await signerToken.mock.balanceOf
+        .withArgs(signer.address)
+        .returns(DEFAULT_SIGNER_AMOUNT - 1)
+
       await expect(
         delegate.connect(signer).swap(sender.address, ...order)
-      ).to.revertedWith('RuleExpired')
+      ).to.be.revertedWith('SignerAmountInvalid')
     })
   })
 })