diff --git a/test/forge/PermitTest.sol b/test/forge/PermitTest.sol
index ce7028a0..75a50e87 100644
--- a/test/forge/PermitTest.sol
+++ b/test/forge/PermitTest.sol
@@ -5,8 +5,6 @@ import "./helpers/SigUtils.sol";
 import "./helpers/BaseTest.sol";
 
 contract PermitTest is BaseTest {
-    SigUtils internal sigUtils;
-
     uint256 internal constant OWNER_PK = 0xA11CE;
     uint256 internal constant SPENDER_PK = 0xB0B;
 
@@ -16,8 +14,6 @@ contract PermitTest is BaseTest {
     function setUp() public override {
         super.setUp();
 
-        sigUtils = new SigUtils(vault.DOMAIN_SEPARATOR());
-
         owner = vm.addr(OWNER_PK);
         spender = vm.addr(SPENDER_PK);
 
@@ -27,8 +23,7 @@ contract PermitTest is BaseTest {
     function testPermit() public {
         Permit memory permit = Permit({owner: owner, spender: spender, value: 1e18, nonce: 0, deadline: 1 days});
 
-        bytes32 digest = sigUtils.getTypedDataHash(permit);
-
+        bytes32 digest = SigUtils.toTypedDataHash(vault.DOMAIN_SEPARATOR(), permit);
         (uint8 v, bytes32 r, bytes32 s) = vm.sign(OWNER_PK, digest);
 
         vault.permit(permit.owner, permit.spender, permit.value, permit.deadline, v, r, s);
@@ -41,8 +36,7 @@ contract PermitTest is BaseTest {
         Permit memory permit =
             Permit({owner: owner, spender: spender, value: 1e18, nonce: vault.nonces(owner), deadline: 1 days});
 
-        bytes32 digest = sigUtils.getTypedDataHash(permit);
-
+        bytes32 digest = SigUtils.toTypedDataHash(vault.DOMAIN_SEPARATOR(), permit);
         (uint8 v, bytes32 r, bytes32 s) = vm.sign(OWNER_PK, digest);
 
         vm.warp(1 days + 1 seconds); // fast forward one second past the deadline
@@ -55,8 +49,7 @@ contract PermitTest is BaseTest {
         Permit memory permit =
             Permit({owner: owner, spender: spender, value: 1e18, nonce: vault.nonces(owner), deadline: 1 days});
 
-        bytes32 digest = sigUtils.getTypedDataHash(permit);
-
+        bytes32 digest = SigUtils.toTypedDataHash(vault.DOMAIN_SEPARATOR(), permit);
         (uint8 v, bytes32 r, bytes32 s) = vm.sign(SPENDER_PK, digest); // spender signs owner's approval
 
         vm.expectRevert("ERC20Permit: invalid signature");
@@ -72,8 +65,7 @@ contract PermitTest is BaseTest {
             deadline: 1 days
         });
 
-        bytes32 digest = sigUtils.getTypedDataHash(permit);
-
+        bytes32 digest = SigUtils.toTypedDataHash(vault.DOMAIN_SEPARATOR(), permit);
         (uint8 v, bytes32 r, bytes32 s) = vm.sign(OWNER_PK, digest);
 
         vm.expectRevert("ERC20Permit: invalid signature");
@@ -83,8 +75,7 @@ contract PermitTest is BaseTest {
     function testRevertSignatureReplay() public {
         Permit memory permit = Permit({owner: owner, spender: spender, value: 1e18, nonce: 0, deadline: 1 days});
 
-        bytes32 digest = sigUtils.getTypedDataHash(permit);
-
+        bytes32 digest = SigUtils.toTypedDataHash(vault.DOMAIN_SEPARATOR(), permit);
         (uint8 v, bytes32 r, bytes32 s) = vm.sign(OWNER_PK, digest);
 
         vault.permit(permit.owner, permit.spender, permit.value, permit.deadline, v, r, s);
@@ -96,8 +87,7 @@ contract PermitTest is BaseTest {
     function testTransferFromLimitedPermit() public {
         Permit memory permit = Permit({owner: owner, spender: spender, value: 1e18, nonce: 0, deadline: 1 days});
 
-        bytes32 digest = sigUtils.getTypedDataHash(permit);
-
+        bytes32 digest = SigUtils.toTypedDataHash(vault.DOMAIN_SEPARATOR(), permit);
         (uint8 v, bytes32 r, bytes32 s) = vm.sign(OWNER_PK, digest);
 
         vault.permit(permit.owner, permit.spender, permit.value, permit.deadline, v, r, s);
@@ -114,8 +104,7 @@ contract PermitTest is BaseTest {
         Permit memory permit =
             Permit({owner: owner, spender: spender, value: type(uint256).max, nonce: 0, deadline: 1 days});
 
-        bytes32 digest = sigUtils.getTypedDataHash(permit);
-
+        bytes32 digest = SigUtils.toTypedDataHash(vault.DOMAIN_SEPARATOR(), permit);
         (uint8 v, bytes32 r, bytes32 s) = vm.sign(OWNER_PK, digest);
 
         vault.permit(permit.owner, permit.spender, permit.value, permit.deadline, v, r, s);
@@ -137,8 +126,7 @@ contract PermitTest is BaseTest {
             deadline: 1 days
         });
 
-        bytes32 digest = sigUtils.getTypedDataHash(permit);
-
+        bytes32 digest = SigUtils.toTypedDataHash(vault.DOMAIN_SEPARATOR(), permit);
         (uint8 v, bytes32 r, bytes32 s) = vm.sign(OWNER_PK, digest);
 
         vault.permit(permit.owner, permit.spender, permit.value, permit.deadline, v, r, s);
@@ -156,8 +144,7 @@ contract PermitTest is BaseTest {
             deadline: 1 days
         });
 
-        bytes32 digest = sigUtils.getTypedDataHash(permit);
-
+        bytes32 digest = SigUtils.toTypedDataHash(vault.DOMAIN_SEPARATOR(), permit);
         (uint8 v, bytes32 r, bytes32 s) = vm.sign(OWNER_PK, digest);
 
         vault.permit(permit.owner, permit.spender, permit.value, permit.deadline, v, r, s);
diff --git a/test/forge/helpers/SigUtils.sol b/test/forge/helpers/SigUtils.sol
index 11d90252..9c8ef5e2 100644
--- a/test/forge/helpers/SigUtils.sol
+++ b/test/forge/helpers/SigUtils.sol
@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 pragma solidity ^0.8.0;
 
+import {ECDSA} from "@openzeppelin/utils/cryptography/ECDSA.sol";
+
 struct Permit {
     address owner;
     address spender;
@@ -9,25 +11,16 @@ struct Permit {
     uint256 deadline;
 }
 
-// keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
-bytes32 constant PERMIT_TYPEHASH = 0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9;
-
-contract SigUtils {
-    bytes32 internal DOMAIN_SEPARATOR;
-
-    constructor(bytes32 _DOMAIN_SEPARATOR) {
-        DOMAIN_SEPARATOR = _DOMAIN_SEPARATOR;
-    }
+bytes32 constant PERMIT_TYPEHASH =
+    keccak256("Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)");
 
-    // computes the hash of a permit
-    function getStructHash(Permit memory _permit) internal pure returns (bytes32) {
-        return keccak256(
-            abi.encode(PERMIT_TYPEHASH, _permit.owner, _permit.spender, _permit.value, _permit.nonce, _permit.deadline)
+library SigUtils {
+    function toTypedDataHash(bytes32 domainSeparator, Permit memory permit) internal pure returns (bytes32) {
+        return ECDSA.toTypedDataHash(
+            domainSeparator,
+            keccak256(
+                abi.encode(PERMIT_TYPEHASH, permit.owner, permit.spender, permit.value, permit.nonce, permit.deadline)
+            )
         );
     }
-
-    // computes the hash of the fully encoded EIP-712 message for the domain, which can be used to recover the signer
-    function getTypedDataHash(Permit memory _permit) public view returns (bytes32) {
-        return keccak256(abi.encodePacked("\x19\x01", DOMAIN_SEPARATOR, getStructHash(_permit)));
-    }
 }