diff --git a/contracts/socket/SocketBatcher.sol b/contracts/socket/SocketBatcher.sol
index 0d00c044..a0606443 100644
--- a/contracts/socket/SocketBatcher.sol
+++ b/contracts/socket/SocketBatcher.sol
@@ -58,7 +58,6 @@ contract SocketBatcher is AccessControl {
      */
     struct AttestRequest {
         bytes32 packetId;
-        uint32 srcChainSlug;
         bytes signature;
     }
 
@@ -306,7 +305,6 @@ contract SocketBatcher is AccessControl {
         for (uint256 index = 0; index < attestRequestslength; ) {
             FastSwitchboard(switchBoardAddress_).attest(
                 attestRequests_[index].packetId,
-                attestRequests_[index].srcChainSlug,
                 attestRequests_[index].signature
             );
             unchecked {
diff --git a/contracts/switchboard/default-switchboards/FastSwitchboard.sol b/contracts/switchboard/default-switchboards/FastSwitchboard.sol
index 2613ce5e..d6e92a88 100644
--- a/contracts/switchboard/default-switchboards/FastSwitchboard.sol
+++ b/contracts/switchboard/default-switchboards/FastSwitchboard.sol
@@ -62,29 +62,29 @@ contract FastSwitchboard is SwitchboardBase {
     /**
      * @dev Function to attest a packet
      * @param packetId_ Packet ID
-     * @param srcChainSlug_ Chain slug of the source chain
      * @param signature_ Signature of the packet
      */
     function attest(
         bytes32 packetId_,
-        uint32 srcChainSlug_,
         bytes calldata signature_
     ) external {
+
+        uint32 srcChainSlug = uint32(uint256(packetId_) >> 224);
         address watcher = SignatureVerifierLib.recoverSignerFromDigest(
             keccak256(
-                abi.encode(address(this), srcChainSlug_, chainSlug, packetId_)
+                abi.encode(address(this), srcChainSlug, chainSlug, packetId_)
             ),
             signature_
         );
 
         if (isAttested[watcher][packetId_]) revert AlreadyAttested();
-        if (!_hasRoleWithSlug(WATCHER_ROLE, srcChainSlug_, watcher))
+        if (!_hasRoleWithSlug(WATCHER_ROLE, srcChainSlug, watcher))
             revert WatcherNotFound();
 
         isAttested[watcher][packetId_] = true;
         attestations[packetId_]++;
 
-        if (attestations[packetId_] >= totalWatchers[srcChainSlug_])
+        if (attestations[packetId_] >= totalWatchers[srcChainSlug])
             isPacketValid[packetId_] = true;
 
         emit PacketAttested(packetId_, watcher);
diff --git a/test/Setup.t.sol b/test/Setup.t.sol
index 3df729b3..65d45c1e 100644
--- a/test/Setup.t.sol
+++ b/test/Setup.t.sol
@@ -488,7 +488,6 @@ contract Setup is Test {
         // attest with packetId_, srcSlug and signature
         FastSwitchboard(switchboardAddress).attest(
             packetId_,
-            srcSlug,
             attestSignature
         );
     }
diff --git a/test/switchboard/default-switchboards/FastSwitchboard.t.sol b/test/switchboard/default-switchboards/FastSwitchboard.t.sol
index 0651672c..d58ed8a3 100644
--- a/test/switchboard/default-switchboards/FastSwitchboard.t.sol
+++ b/test/switchboard/default-switchboards/FastSwitchboard.t.sol
@@ -5,7 +5,7 @@ import "../../Setup.t.sol";
 
 contract FastSwitchboardTest is Setup {
     bool isFast = true;
-    uint32 immutable remoteChainSlug = uint32(uint256(2));
+    uint32 immutable remoteChainSlug = uint32(2);
     bytes32 immutable packetId = bytes32(0);
     address watcher;
     address altWatcher;
@@ -26,7 +26,7 @@ contract FastSwitchboardTest is Setup {
     function setUp() external {
         initialise();
 
-        _a.chainSlug = uint32(uint256(1));
+        _a.chainSlug = uint32(1);
         vm.startPrank(_socketOwner);
 
         fastSwitchboard = new FastSwitchboard(
@@ -106,7 +106,7 @@ contract FastSwitchboardTest is Setup {
         vm.expectEmit(false, false, false, true);
         emit PacketAttested(packetId, watcher);
 
-        fastSwitchboard.attest(packetId, remoteChainSlug, sig);
+        fastSwitchboard.attest(packetId, sig);
 
         assertTrue(fastSwitchboard.isAttested(watcher, packetId));
     }
@@ -125,12 +125,12 @@ contract FastSwitchboardTest is Setup {
         vm.expectEmit(false, false, false, true);
         emit PacketAttested(packetId, watcher);
 
-        fastSwitchboard.attest(packetId, remoteChainSlug, sig);
+        fastSwitchboard.attest(packetId, sig);
 
         assertTrue(fastSwitchboard.isAttested(watcher, packetId));
 
         vm.expectRevert(AlreadyAttested.selector);
-        fastSwitchboard.attest(packetId, remoteChainSlug, sig);
+        fastSwitchboard.attest(packetId, sig);
     }
 
     function testIsAllowed() external {
@@ -144,7 +144,7 @@ contract FastSwitchboardTest is Setup {
         );
         bytes memory sig = _createSignature(digest, _watcherPrivateKey);
 
-        fastSwitchboard.attest(packetId, remoteChainSlug, sig);
+        fastSwitchboard.attest(packetId, sig);
 
         digest = keccak256(
             abi.encode(
@@ -156,7 +156,7 @@ contract FastSwitchboardTest is Setup {
         );
         sig = _createSignature(digest, _altWatcherPrivateKey);
 
-        fastSwitchboard.attest(packetId, remoteChainSlug, sig);
+        fastSwitchboard.attest(packetId, sig);
 
         uint256 proposeTime = block.timestamp -
             fastSwitchboard.timeoutInSeconds();
@@ -344,6 +344,26 @@ contract FastSwitchboardTest is Setup {
         bytes memory sig = "0x121234323123232323";
 
         vm.expectRevert(InvalidSigLength.selector);
-        fastSwitchboard.attest(packetId, remoteChainSlug, sig);
+        fastSwitchboard.attest(packetId, sig);
+    }
+
+
+    function testAttesterCantAttestAllChains() public {
+
+        // Packet is coming from a chain different from remoteChainSlug
+        bytes32 altPacketId = bytes32(uint256(100)<<224);
+
+        bytes32 digest = keccak256(
+            abi.encode(
+                address(fastSwitchboard),
+                remoteChainSlug,
+                _a.chainSlug,
+                altPacketId
+            )
+        );
+        bytes memory sig = _createSignature(digest, _watcherPrivateKey);
+
+        vm.expectRevert(WatcherNotFound.selector);
+        fastSwitchboard.attest(altPacketId, sig);
     }
 }