diff --git a/foundry/src/uniswap_x/UniswapXFiller.sol b/foundry/src/uniswap_x/UniswapXFiller.sol
index de52edd..1156c31 100644
--- a/foundry/src/uniswap_x/UniswapXFiller.sol
+++ b/foundry/src/uniswap_x/UniswapXFiller.sol
@@ -11,6 +11,7 @@ import "@openzeppelin/contracts/access/AccessControl.sol";
 import "@openzeppelin/contracts/utils/Address.sol";
 
 error UniswapXFiller__AddressZero();
+error UniswapXFiller__BatchExecutionNotSupported();
 
 contract UniswapXFiller is AccessControl, IReactorCallback {
     using SafeERC20 for IERC20;
@@ -34,7 +35,7 @@ contract UniswapXFiller is AccessControl, IReactorCallback {
         if (_reactor == address(0)) revert UniswapXFiller__AddressZero();
 
         _grantRole(DEFAULT_ADMIN_ROLE, msg.sender);
-        _grantRole(REACTOR_ROLE, address(reactor));
+        _grantRole(REACTOR_ROLE, address(_reactor));
         tychoRouter = _tychoRouter;
         reactor = IReactor(_reactor);
     }
@@ -50,7 +51,34 @@ contract UniswapXFiller is AccessControl, IReactorCallback {
         ResolvedOrder[] calldata resolvedOrders,
         bytes calldata callbackData
     ) external onlyRole(REACTOR_ROLE) {
-        // TODO
+        require(
+            resolvedOrders.length == 1,
+            UniswapXFiller__BatchExecutionNotSupported()
+        );
+
+        ResolvedOrder memory order = resolvedOrders[0];
+
+        // TODO properly handle native in and out tokens
+        uint256 ethValue = 0;
+
+        // slither-disable-next-line low-level-calls
+        (bool success, bytes memory result) =
+            tychoRouter.call{value: ethValue}(callbackData);
+
+        if (!success) {
+            revert(
+                string(
+                    result.length > 0
+                        ? result
+                        : abi.encodePacked("Execution failed")
+                )
+            );
+        }
+
+        // Multiple outputs are possible when taking fees - but token itself should
+        // not change.
+        IERC20 token = IERC20(order.outputs[0].token);
+        token.forceApprove(address(reactor), type(uint256).max);
     }
 
     /**
@@ -103,6 +131,7 @@ contract UniswapXFiller is AccessControl, IReactorCallback {
     /**
      * @dev Allows this contract to receive native token with empty msg.data from contracts
      */
+    // slither-disable-next-line locked-ether
     receive() external payable {
         require(msg.sender.code.length != 0);
     }
diff --git a/foundry/test/uniswap_x/UniswapXFiller.t.sol b/foundry/test/uniswap_x/UniswapXFiller.t.sol
index 1dc11df..8102e4f 100644
--- a/foundry/test/uniswap_x/UniswapXFiller.t.sol
+++ b/foundry/test/uniswap_x/UniswapXFiller.t.sol
@@ -17,6 +17,10 @@ contract UniswapXFillerTest is Test, TychoRouterTestSetup {
         address indexed token, uint256 amount, address indexed receiver
     );
 
+    function getForkBlock() public pure override returns (uint256) {
+        return 22788691;
+    }
+
     function fillerSetup() public {
         vm.startPrank(ADMIN);
         filler = new UniswapXFiller(tychoRouterAddr, REACTOR);
@@ -35,6 +39,126 @@ contract UniswapXFillerTest is Test, TychoRouterTestSetup {
         filler = new UniswapXFiller(tychoRouterAddr, address(0));
     }
 
+    function testCallback() public {
+        fillerSetup();
+        uint256 amountIn = 10 ** 18;
+        uint256 amountOut = 1847751195973566072891;
+        bool zeroForOne = false;
+        bytes memory protocolData = abi.encodePacked(
+            WETH_ADDR,
+            WETH_DAI_POOL,
+            address(filler),
+            zeroForOne,
+            RestrictTransferFrom.TransferType.TransferFrom
+        );
+
+        bytes memory swap =
+            encodeSingleSwap(address(usv2Executor), protocolData);
+
+        bytes memory callbackData = abi.encodeWithSelector(
+            tychoRouter.singleSwap.selector,
+            amountIn,
+            WETH_ADDR,
+            DAI_ADDR,
+            2008817438608734439722,
+            false,
+            false,
+            address(filler),
+            true,
+            swap
+        );
+
+        deal(WETH_ADDR, address(filler), amountIn);
+        vm.startPrank(address(filler));
+        IERC20(WETH_ADDR).approve(tychoRouterAddr, amountIn);
+        vm.stopPrank();
+        ResolvedOrder[] memory orders = new ResolvedOrder[](1);
+        OutputToken[] memory outputs = new OutputToken[](1);
+        outputs[0] = OutputToken({
+            token: address(DAI_ADDR),
+            // Irrelevant fields - we only need the token address for approval
+            amount: 1847751195973566072891,
+            recipient: BOB
+        });
+        // All irrelevant fields for this test - we only need the output token address
+        orders[0] = ResolvedOrder({
+            info: OrderInfo({
+                reactor: address(0),
+                swapper: address(0),
+                nonce: 0,
+                deadline: 0,
+                additionalValidationContract: address(0),
+                additionalValidationData: ""
+            }),
+            input: InputToken({token: address(WETH_ADDR), amount: 0, maxAmount: 0}),
+            outputs: outputs,
+            sig: "",
+            hash: ""
+        });
+
+        vm.startPrank(REACTOR);
+        filler.reactorCallback(orders, callbackData);
+        vm.stopPrank();
+
+        // Check that the funds are in the filler at the end of the function call
+        uint256 finalBalance = IERC20(DAI_ADDR).balanceOf(address(filler));
+        assertGe(finalBalance, amountOut);
+
+        // Check that the proper approval was set
+        vm.startPrank(REACTOR);
+        IERC20(DAI_ADDR).transferFrom(address(filler), BOB, amountOut);
+        vm.stopPrank();
+        assertGe(IERC20(DAI_ADDR).balanceOf(BOB), amountOut);
+    }
+
+    function testExecuteIntegration() public {
+        fillerSetup();
+        // tx: 0x5b602b7d0a37e241bd032a907b9ddf314e9f2fc2104fd91cb55bdb3d8dfe4e9c
+        // 0.2 WBTC -> USDC
+        SignedOrder memory order = SignedOrder({
+            order: hex"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",
+            sig: hex"41b7a696a04f897d1e4ccaf88136092169c2874242d55c3fe4c028125efe95340f5ce764b9dce9d2cae241d97ceb515d3f1739972ca884ed51b2870045438c3a1c"
+        });
+
+        uint256 amountIn = 0.2 * 10 ** 8;
+        bool zeroForOne = true;
+        bytes memory protocolData = abi.encodePacked(
+            WBTC_ADDR,
+            USDC_WBTC_POOL,
+            fillerAddr,
+            zeroForOne,
+            RestrictTransferFrom.TransferType.TransferFrom
+        );
+
+        bytes memory swap =
+            encodeSingleSwap(address(usv2Executor), protocolData);
+
+        bytes memory callbackData = abi.encodeWithSelector(
+            tychoRouter.singleSwap.selector,
+            amountIn,
+            WBTC_ADDR,
+            USDC_ADDR,
+            1,
+            false,
+            false,
+            fillerAddr,
+            true,
+            swap
+        );
+
+        vm.startPrank(address(filler));
+        IERC20(WBTC_ADDR).approve(tychoRouterAddr, amountIn);
+        vm.stopPrank();
+
+        // This is a hack because the tx we are trying to replicate returns a looooot more USDC than what the uni v2 pool does at this point
+        // 5113180081 is the difference and 54068100 is the fee
+        deal(USDC_ADDR, address(filler), 5113180081 + 54068100);
+
+        vm.startPrank(EXECUTOR);
+        filler.execute(order, callbackData);
+        vm.stopPrank();
+    }
+
     function testWithdrawNative() public {
         fillerSetup();
         vm.startPrank(ADMIN);