diff --git a/evm/forge/tests/ForkSlots.t.sol b/evm/forge/tests/ForkSlots.t.sol
new file mode 100644
index 0000000..c9b8019
--- /dev/null
+++ b/evm/forge/tests/ForkSlots.t.sol
@@ -0,0 +1,236 @@
+// SPDX-License-Identifier: Apache 2
+pragma solidity ^0.8.22;
+
+import "forge-std/Test.sol";
+import "forge-std/console.sol";
+
+import {IWormhole} from "src/interfaces/IWormhole.sol";
+import {ICircleIntegration} from "src/interfaces/ICircleIntegration.sol";
+
+import {Utils} from "src/libraries/Utils.sol";
+
+import {Implementation} from "src/contracts/CircleIntegration/Implementation.sol";
+
+import {
+    CircleIntegrationOverride,
+    CraftedCctpMessageParams,
+    CraftedVaaParams
+} from "test-helpers/libraries/CircleIntegrationOverride.sol";
+import {UsdcDeal} from "test-helpers/libraries/UsdcDeal.sol";
+import {WormholeOverride} from "test-helpers/libraries/WormholeOverride.sol";
+
+contract ForkSlots is Test {
+    using CircleIntegrationOverride for *;
+    using WormholeOverride for *;
+    using Utils for address;
+
+    bytes32 constant GOVERNANCE_MODULE =
+        0x000000000000000000000000000000436972636c65496e746567726174696f6e;
+
+    address constant FORKED_CIRCLE_INTEGRATION_ADDRESS = 0x2703483B1a5a7c577e8680de9Df8Be03c6f30e3c;
+
+    ICircleIntegration forked;
+    IWormhole wormhole;
+
+    function setUp() public {
+        forked = ICircleIntegration(FORKED_CIRCLE_INTEGRATION_ADDRESS);
+        forked.setUpOverride(uint256(vm.envBytes32("TESTING_DEVNET_GUARDIAN")));
+
+        wormhole = forked.wormhole();
+    }
+
+    function test_UpgradeForkAndCheckSlots() public {
+        // Deploy new implementation.
+        Implementation implementation = new Implementation(
+            address(wormhole),
+            vm.envAddress("TESTING_CIRCLE_BRIDGE_ADDRESS") // tokenMessenger
+        );
+
+        // Should not be initialized yet.
+        assertFalse(forked.isInitialized(address(implementation)), "already initialized");
+
+        // Also verify slot reflects same information.
+        {
+            bytes32 data = vm.load(
+                address(forked), keccak256(abi.encode(address(implementation), uint256(0x5)))
+            );
+            assertEq(
+                uint256(data),
+                0, // false
+                "isInitialized does not match slot value (false)"
+            );
+        }
+
+        // Check slots 0x0, 0x1, 0x2, 0x3, 0x4 and 0xa before upgrade.
+
+        // 0x0:
+        //
+        // uint16 chainId;
+        // uint8 wormholeFinality;
+        // uint32 localDomain;
+        // address wormhole;
+        // uint16 governanceChainId;
+        {
+            bytes32 data = vm.load(address(forked), bytes32(0));
+
+            uint256 bitOffset;
+
+            // First 2 bytes is chain ID.
+            assertEq(uint16(uint256(data >> bitOffset)), forked.chainId());
+            bitOffset += 16;
+
+            // Next byte is wormhole finality.
+            assertEq(uint8(uint256(data >> bitOffset)), forked.wormholeFinality());
+            bitOffset += 8;
+
+            // Next 4 bytes is local domain.
+            assertEq(uint32(uint256(data >> bitOffset)), forked.localDomain());
+            bitOffset += 32;
+
+            // Next 20 bytes is wormhole address.
+            assertEq(address(uint160(uint256(data >> bitOffset))), address(wormhole));
+            bitOffset += 160;
+
+            // Next 2 bytes is governance chain ID.
+            assertEq(uint16(uint256(data >> bitOffset)), forked.governanceChainId());
+            bitOffset += 16;
+
+            // Remaining bytes are zero.
+            assertEq(uint256(data >> bitOffset), 0);
+        }
+
+        // 0x1:
+        //
+        // governanceContract
+        {
+            bytes32 data = vm.load(address(forked), bytes32(uint256(0x1)));
+            assertEq(data, forked.governanceContract());
+        }
+
+        // 0x2:
+        //
+        // circleBridgeAddress
+        {
+            bytes32 data = vm.load(address(forked), bytes32(uint256(0x2)));
+            assertEq(address(uint160(uint256(data))), address(forked.circleBridge()));
+        }
+
+        // 0x3:
+        //
+        // circleTransmitterAddress
+        {
+            bytes32 data = vm.load(address(forked), bytes32(uint256(0x3)));
+            assertEq(address(uint160(uint256(data))), address(forked.circleTransmitter()));
+        }
+
+        // 0x4:
+        //
+        // circleTokenMinterAddress
+        {
+            bytes32 data = vm.load(address(forked), bytes32(uint256(0x4)));
+            assertEq(address(uint160(uint256(data))), address(forked.circleTokenMinter()));
+        }
+
+        // 0xa:
+        //
+        // evmChain
+        {
+            bytes32 data = vm.load(address(forked), bytes32(uint256(0xa)));
+            assertEq(uint256(data), forked.evmChain());
+        }
+
+        // Before upgrading, fetch some expected values.
+        uint16 registeredChainId = 2;
+        bytes32 expectedEmitter = forked.getRegisteredEmitter(registeredChainId);
+
+        // Also verify slot reflects same information.
+        {
+            bytes32 data =
+                vm.load(address(forked), keccak256(abi.encode(registeredChainId, uint256(0x6))));
+            assertEq(data, expectedEmitter);
+        }
+
+        uint32 expectedCctpDomain = forked.getDomainFromChainId(registeredChainId);
+
+        // Also verify slot reflects same information.
+        {
+            bytes32 data =
+                vm.load(address(forked), keccak256(abi.encode(registeredChainId, uint256(0x7))));
+            assertEq(uint32(uint256(data)), expectedCctpDomain);
+        }
+
+        assertEq(forked.getChainIdFromDomain(expectedCctpDomain), registeredChainId);
+
+        // Also verify slot reflects same information.
+        {
+            bytes32 data =
+                vm.load(address(forked), keccak256(abi.encode(expectedCctpDomain, uint256(0x8))));
+            assertEq(uint16(uint256(data)), registeredChainId);
+        }
+
+        (IWormhole.VM memory vaa, bytes memory encodedVaa) = wormhole.craftGovernanceVaa(
+            GOVERNANCE_MODULE,
+            3, // action
+            forked.chainId(),
+            69, // sequence
+            abi.encodePacked(address(implementation).toUniversalAddress())
+        );
+
+        // Show that VAA has not been consumed yet.
+        assertFalse(forked.isMessageConsumed(vaa.hash), "VAA already consumed");
+
+        // Also verify slot reflects same information.
+        {
+            bytes32 data = vm.load(address(forked), keccak256(abi.encode(vaa.hash, uint256(0x9))));
+            assertEq(
+                uint256(data),
+                0, // false
+                "isMessageConsumed does not match slot value (true)"
+            );
+        }
+
+        // Upgrade contract.
+        forked.upgradeContract(encodedVaa);
+
+        // Now initialized.
+        assertTrue(forked.isInitialized(address(implementation)), "implementation not initialized");
+
+        // Also verify slot reflects same information.
+        {
+            bytes32 data = vm.load(
+                address(forked), keccak256(abi.encode(address(implementation), uint256(0x5)))
+            );
+            assertEq(
+                uint256(data),
+                1, // true
+                "isInitialized does not match slot value (true)"
+            );
+        }
+
+        // Show that VAA is now consumed.
+        assertTrue(forked.isMessageConsumed(vaa.hash), "VAA not consumed");
+
+        // Also verify slot reflects same information.
+        {
+            bytes32 data = vm.load(address(forked), keccak256(abi.encode(vaa.hash, uint256(0x9))));
+            assertEq(
+                uint256(data),
+                1, // true
+                "isMessageConsumed does not match slot value (true)"
+            );
+        }
+
+        // Slots checked above should now be zero.
+        {
+            uint256[6] memory slots =
+                [0, uint256(0x1), uint256(0x2), uint256(0x3), uint256(0x4), uint256(0xa)];
+            for (uint256 i; i < slots.length;) {
+                bytes32 data = vm.load(address(forked), bytes32(slots[i]));
+                assertEq(uint256(data), 0);
+                unchecked {
+                    ++i;
+                }
+            }
+        }
+    }
+}
diff --git a/evm/forge/tests/gas/CircleIntegrationComparison.t.sol b/evm/forge/tests/gas/CircleIntegrationComparison.t.sol
index 82b74f3..2598d36 100644
--- a/evm/forge/tests/gas/CircleIntegrationComparison.t.sol
+++ b/evm/forge/tests/gas/CircleIntegrationComparison.t.sol
@@ -38,7 +38,7 @@ contract CircleIntegrationComparison is Test {
     bytes32 immutable FOREIGN_USDC_ADDRESS =
         bytes32(uint256(uint160(vm.envAddress("TESTING_FOREIGN_USDC_TOKEN_ADDRESS"))));
 
-    address immutable FORKED_CIRCLE_INTEGRATION_ADDRESS = 0x2703483B1a5a7c577e8680de9Df8Be03c6f30e3c;
+    address constant FORKED_CIRCLE_INTEGRATION_ADDRESS = 0x2703483B1a5a7c577e8680de9Df8Be03c6f30e3c;
 
     // dependencies
     IWormhole wormhole;
diff --git a/evm/forge/tests/helpers/libraries/WormholeOverride.sol b/evm/forge/tests/helpers/libraries/WormholeOverride.sol
index db09557..6151035 100644
--- a/evm/forge/tests/helpers/libraries/WormholeOverride.sol
+++ b/evm/forge/tests/helpers/libraries/WormholeOverride.sol
@@ -168,4 +168,21 @@ library WormholeOverride {
             encodedBody
         );
     }
+
+    function craftGovernanceVaa(
+        IWormhole wormhole,
+        bytes32 module,
+        uint8 action,
+        uint16 targetChain,
+        uint64 sequence,
+        bytes memory decree
+    ) internal view returns (IWormhole.VM memory vaa, bytes memory encoded) {
+        (vaa, encoded) = craftVaa(
+            wormhole,
+            GOVERNANCE_CHAIN_ID,
+            GOVERNANCE_CONTRACT,
+            sequence,
+            abi.encodePacked(module, action, targetChain, decree)
+        );
+    }
 }