diff --git a/contracts/src/utils/ECDSA.sol b/contracts/src/utils/ECDSA.sol
index 821936ad..f6112ccb 100644
--- a/contracts/src/utils/ECDSA.sol
+++ b/contracts/src/utils/ECDSA.sol
@@ -31,7 +31,7 @@ library ECDSA {
 
         if (signer == address(0)) return false;
 
-        bytes memory publicKeyBytes = abi.encodePacked(bytes1(0x04), publicKey.x, publicKey.y);
+        bytes memory publicKeyBytes = abi.encodePacked(publicKey.x, publicKey.y);
 
         bytes32 publicKeyHash = keccak256(publicKeyBytes);
 
diff --git a/contracts/test/account/ExperimentalDelegation.t.sol b/contracts/test/account/ExperimentalDelegation.t.sol
index cc36541f..b7d20d56 100644
--- a/contracts/test/account/ExperimentalDelegation.t.sol
+++ b/contracts/test/account/ExperimentalDelegation.t.sol
@@ -88,6 +88,31 @@ contract ExperimentalDelegationTest is Test {
         assertEq(expiry, 0);
     }
 
+    function test_authorize_withSecp256k1Key() public {
+        vm.pauseGasMetering();
+
+        VmSafe.Wallet memory wallet = vm.createWallet("wallet");
+
+        ExperimentalDelegation.Key[] memory keys = new ExperimentalDelegation.Key[](1);
+        keys[0] = ExperimentalDelegation.Key(
+            0, ExperimentalDelegation.KeyType.Secp256k1, ECDSA.PublicKey(wallet.publicKeyX, wallet.publicKeyY)
+        );
+
+        vm.expectRevert();
+        delegation.keys(0);
+
+        vm.prank(address(delegation));
+        vm.resumeGasMetering();
+        delegation.authorize(keys);
+        vm.pauseGasMetering();
+
+        (uint256 expiry, ExperimentalDelegation.KeyType keyType, ECDSA.PublicKey memory authorizedPublicKey) =
+            delegation.keys(0);
+        assertEq(authorizedPublicKey.x, wallet.publicKeyX);
+        assertEq(authorizedPublicKey.y, wallet.publicKeyY);
+        assertEq(expiry, 0);
+    }
+
     function test_authorize_withAuthorizedKey() public {
         vm.pauseGasMetering();
 
@@ -322,4 +347,27 @@ contract ExperimentalDelegationTest is Test {
             bytes4(keccak256("isValidSignature(bytes32,bytes)"))
         );
     }
+
+    function test_isValidSignature_forAuthorizingSecp256k1Key() public {
+        bytes32 hash = keccak256(abi.encodePacked(delegation.nonce(), keccak256("0xdeadbeef")));
+        VmSafe.Wallet memory wallet = vm.createWallet("wallet");
+
+        ExperimentalDelegation.Key[] memory keys = new ExperimentalDelegation.Key[](1);
+        keys[0] = ExperimentalDelegation.Key(
+            0, ExperimentalDelegation.KeyType.Secp256k1, ECDSA.PublicKey(wallet.publicKeyX, wallet.publicKeyY)
+        );
+
+        vm.prank(address(delegation));
+        delegation.authorize(keys);
+
+        (uint8 v, bytes32 r, bytes32 s) = vm.sign(wallet.privateKey, hash);
+        ExperimentalDelegation.WrappedSignature memory wrappedSignature = ExperimentalDelegation.WrappedSignature(
+            0, ECDSA.Signature(uint256(r), uint256(s), v == 27 ? 0 : 1), false, "0x"
+        );
+
+        assertEq(
+            delegation.isValidSignature(hash, abi.encode(wrappedSignature)),
+            bytes4(keccak256("isValidSignature(bytes32,bytes)"))
+        );
+    }
 }