diff --git a/test/protocol/switchboard/EVMxSwitchboard.t.sol b/test/protocol/switchboard/EVMxSwitchboard.t.sol
index cf979b30..eaecdf67 100644
--- a/test/protocol/switchboard/EVMxSwitchboard.t.sol
+++ b/test/protocol/switchboard/EVMxSwitchboard.t.sol
@@ -279,19 +279,22 @@ contract EVMxSwitchboardTestBase is Test, Utils {
      * @dev Helper to create signature for assignTransmitter given digest params and new transmitter
      * @param digestParams_ The digest parameters (will be modified to use new transmitter)
      * @param newTransmitter_ The new transmitter address
-     * @return signature The signature for the new digest
+     * @return signature The signature for the old and new digest
      */
     function _createAssignTransmitterSignature(
         DigestParams memory digestParams_,
         address newTransmitter_
     ) internal view returns (bytes memory signature) {
+        // Create old digest with current transmitter (before modification)
+        bytes32 oldDigest = createDigest(digestParams_);
+        
         // Create new digest with new transmitter
         digestParams_.transmitter = toBytes32Format(newTransmitter_);
         bytes32 newDigest = createDigest(digestParams_);
 
-        // Create signature for the new digest
+        // Create signature digest with both old and new digests
         bytes32 signatureDigest = keccak256(
-            abi.encodePacked(toBytes32Format(address(evmxSwitchboard)), CHAIN_SLUG, newDigest)
+            abi.encodePacked(toBytes32Format(address(evmxSwitchboard)), CHAIN_SLUG, oldDigest, newDigest)
         );
         signature = createSignature(signatureDigest, watcherPrivateKey);
     }
@@ -1253,13 +1256,16 @@ contract SocketPayloadIdVerificationTest is EVMxSwitchboardTestBase {
         uint256 nonWatcherKey = 0x2222222222222222222222222222222222222222222222222222222222222222;
         address nonWatcher = vm.addr(nonWatcherKey);
 
+        // Create old digest with old transmitter
+        bytes32 oldDigest = createDigest(digestParams);
+        
         // Create new digest with new transmitter
         digestParams.transmitter = toBytes32Format(newTransmitter);
         bytes32 newDigest = createDigest(digestParams);
 
-        // Create signature for the new digest with non-watcher key
+        // Create signature digest with both old and new digests with non-watcher key
         bytes32 signatureDigest = keccak256(
-            abi.encodePacked(toBytes32Format(address(evmxSwitchboard)), CHAIN_SLUG, newDigest)
+            abi.encodePacked(toBytes32Format(address(evmxSwitchboard)), CHAIN_SLUG, oldDigest, newDigest)
         );
         bytes memory signature = createSignature(signatureDigest, nonWatcherKey);