diff --git a/foundry/src/ExecutionDispatcher.sol b/foundry/src/ExecutionDispatcher.sol
index eae85dc..1283b41 100644
--- a/foundry/src/ExecutionDispatcher.sol
+++ b/foundry/src/ExecutionDispatcher.sol
@@ -2,6 +2,7 @@
 pragma solidity ^0.8.26;
 
 import "@interfaces/IExecutor.sol";
+import "forge-std/console.sol";
 
 error ExecutionDispatcher__UnapprovedExecutor();
 error ExecutionDispatcher__NonContractExecutor();
@@ -80,19 +81,25 @@ contract ExecutionDispatcher {
         calculatedAmount = abi.decode(result, (uint256));
     }
 
-    function _handleCallback(bytes calldata data) internal {
-        // Take last 20 bytes (excluding the final byte)
-        address executor =
-            address(bytes20(data[data.length - 21:data.length - 1]));
+    function _handleCallback(bytes4 selector, bytes memory data) internal {
+        // Access the last 20 bytes of the bytes memory data using assembly
+        address executor;
+        // slither-disable-next-line assembly
+        assembly {
+            let pos := sub(add(add(data, 0x20), mload(data)), 20)
+            executor := mload(pos)
+            executor := shr(96, executor)
+        }
 
         if (!executors[executor]) {
             revert ExecutionDispatcher__UnapprovedExecutor();
         }
 
+        selector =
+            selector == bytes4(0) ? IExecutor.handleCallback.selector : selector;
         // slither-disable-next-line controlled-delegatecall,low-level-calls
-        (bool success, bytes memory result) = executor.delegatecall(
-            abi.encodeWithSelector(IExecutor.handleCallback.selector, data)
-        );
+        (bool success, bytes memory result) =
+            executor.delegatecall(abi.encodeWithSelector(selector, data));
 
         if (!success) {
             revert(
diff --git a/foundry/src/TychoRouter.sol b/foundry/src/TychoRouter.sol
index 15e45c3..8084afc 100644
--- a/foundry/src/TychoRouter.sol
+++ b/foundry/src/TychoRouter.sol
@@ -15,6 +15,7 @@ import "./ExecutionDispatcher.sol";
 import {LibSwap} from "../lib/LibSwap.sol";
 import {IPoolManager} from "@uniswap/v4-core/src/interfaces/IPoolManager.sol";
 import {SafeCallback} from "@uniswap/v4-periphery/src/base/SafeCallback.sol";
+import "forge-std/console.sol";
 
 error TychoRouter__WithdrawalFailed();
 error TychoRouter__AddressZero();
@@ -228,9 +229,10 @@ contract TychoRouter is
      * This function will static call a verifier contract and should revert if the
      *  caller is not a pool.
      */
-    fallback() external {
-        _handleCallback(msg.data);
-    }
+    // fallback() external {
+    //     bytes4 selector = bytes4(msg.data[:4]);
+    //     _handleCallback(selector, msg.data[4:]);
+    // }
 
     /**
      * @dev Pauses the contract
@@ -388,6 +390,20 @@ contract TychoRouter is
      */
     receive() external payable {}
 
+    /**
+     * @dev Called by UniswapV3 pool when swapping on it.
+     * See in IUniswapV3SwapCallback for documentation.
+     */
+    function uniswapV3SwapCallback(
+        int256 amount0Delta,
+        int256 amount1Delta,
+        bytes calldata msgData
+    ) external {
+        _handleCallback(
+            bytes4(0), abi.encodePacked(amount0Delta, amount1Delta, msgData)
+        );
+    }
+
     function _unlockCallback(bytes calldata data)
         internal
         override
diff --git a/foundry/src/executors/UniswapV3Executor.sol b/foundry/src/executors/UniswapV3Executor.sol
index f5b6c06..906c771 100644
--- a/foundry/src/executors/UniswapV3Executor.sol
+++ b/foundry/src/executors/UniswapV3Executor.sol
@@ -5,6 +5,7 @@ import "@interfaces/IExecutor.sol";
 import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
 import "@uniswap/v3-core/contracts/interfaces/IUniswapV3Pool.sol";
 import "@uniswap/v3-updated/CallbackValidationV2.sol";
+import "forge-std/console.sol";
 
 error UniswapV3Executor__InvalidDataLength();
 error UniswapV3Executor__InvalidFactory();
@@ -69,11 +70,10 @@ contract UniswapV3Executor is IExecutor {
         external
         returns (bytes memory result)
     {
-        // Skip first 4 bytes of function selector and decode the two int256 values
         (int256 amount0Delta, int256 amount1Delta) =
-            abi.decode(msgData[4:68], (int256, int256));
+            abi.decode(msgData[:64], (int256, int256));
 
-        bytes calldata remainingData = msgData[68:];
+        bytes calldata remainingData = msgData[64:];
 
         (uint256 amountOwed, address tokenOwed) =
             _verifyUSV3Callback(amount0Delta, amount1Delta, remainingData);
@@ -87,9 +87,6 @@ contract UniswapV3Executor is IExecutor {
         int256 amount1Delta,
         bytes calldata data
     ) internal view returns (uint256 amountIn, address tokenIn) {
-        // Skip the first 64 bytes (32 bytes offset + 32 bytes length)
-        data = data[64:];
-
         tokenIn = address(bytes20(data[0:20]));
         address tokenOut = address(bytes20(data[20:40]));
         uint24 poolFee = uint24(bytes3(data[40:43]));