diff --git a/.forge-snapshots/RouterBytecode.snap b/.forge-snapshots/RouterBytecode.snap
index 19b15e18..17ac8e65 100644
--- a/.forge-snapshots/RouterBytecode.snap
+++ b/.forge-snapshots/RouterBytecode.snap
@@ -1 +1 @@
-5925
\ No newline at end of file
+6067
\ No newline at end of file
diff --git a/.forge-snapshots/RouterExactIn1Hop.snap b/.forge-snapshots/RouterExactIn1Hop.snap
index 3bfc7e5a..017f6b15 100644
--- a/.forge-snapshots/RouterExactIn1Hop.snap
+++ b/.forge-snapshots/RouterExactIn1Hop.snap
@@ -1 +1 @@
-101468
\ No newline at end of file
+101510
\ No newline at end of file
diff --git a/.forge-snapshots/RouterExactIn2Hops.snap b/.forge-snapshots/RouterExactIn2Hops.snap
index 6f6b2383..517bb875 100644
--- a/.forge-snapshots/RouterExactIn2Hops.snap
+++ b/.forge-snapshots/RouterExactIn2Hops.snap
@@ -1 +1 @@
-160449
\ No newline at end of file
+160475
\ No newline at end of file
diff --git a/.forge-snapshots/RouterExactIn3Hops.snap b/.forge-snapshots/RouterExactIn3Hops.snap
index 3031f4e5..028f0b10 100644
--- a/.forge-snapshots/RouterExactIn3Hops.snap
+++ b/.forge-snapshots/RouterExactIn3Hops.snap
@@ -1 +1 @@
-212680
\ No newline at end of file
+212691
\ No newline at end of file
diff --git a/.forge-snapshots/RouterExactInputSingle.snap b/.forge-snapshots/RouterExactInputSingle.snap
index 495f97ed..558ce33b 100644
--- a/.forge-snapshots/RouterExactInputSingle.snap
+++ b/.forge-snapshots/RouterExactInputSingle.snap
@@ -1 +1 @@
-106771
\ No newline at end of file
+106775
\ No newline at end of file
diff --git a/.forge-snapshots/RouterExactOut1Hop.snap b/.forge-snapshots/RouterExactOut1Hop.snap
index b08c4f7e..727daa90 100644
--- a/.forge-snapshots/RouterExactOut1Hop.snap
+++ b/.forge-snapshots/RouterExactOut1Hop.snap
@@ -1 +1 @@
-102242
\ No newline at end of file
+102284
\ No newline at end of file
diff --git a/.forge-snapshots/RouterExactOut2Hops.snap b/.forge-snapshots/RouterExactOut2Hops.snap
index f9da51bb..2e896618 100644
--- a/.forge-snapshots/RouterExactOut2Hops.snap
+++ b/.forge-snapshots/RouterExactOut2Hops.snap
@@ -1 +1 @@
-159812
\ No newline at end of file
+159838
\ No newline at end of file
diff --git a/.forge-snapshots/RouterExactOut3Hops.snap b/.forge-snapshots/RouterExactOut3Hops.snap
index 7563d22f..344aedc5 100644
--- a/.forge-snapshots/RouterExactOut3Hops.snap
+++ b/.forge-snapshots/RouterExactOut3Hops.snap
@@ -1 +1 @@
-212732
\ No newline at end of file
+212743
\ No newline at end of file
diff --git a/.forge-snapshots/RouterExactOutputSingle.snap b/.forge-snapshots/RouterExactOutputSingle.snap
index 0a49af3a..91ebf967 100644
--- a/.forge-snapshots/RouterExactOutputSingle.snap
+++ b/.forge-snapshots/RouterExactOutputSingle.snap
@@ -1 +1 @@
-105380
\ No newline at end of file
+105384
\ No newline at end of file
diff --git a/contracts/V4Router.sol b/contracts/V4Router.sol
index 49642064..f4266565 100644
--- a/contracts/V4Router.sol
+++ b/contracts/V4Router.sol
@@ -23,8 +23,10 @@ abstract contract V4Router is IV4Router {
         poolManager = _poolManager;
     }
 
-    function _v4Swap(SwapType swapType, bytes memory params) internal {
-        poolManager.unlock(abi.encode(SwapInfo(swapType, msg.sender, params)));
+    // @dev The contract inheriting from this contract, and calling _v4Swap must set the payer and recipient securely.
+    // Allowing any payer or recipient to be passed in could allow users to steal each others' tokens.
+    function _v4Swap(SwapType swapType, PaymentAddresses memory paymentAddresses, bytes memory params) internal {
+        poolManager.unlock(abi.encode(SwapInfo(swapType, paymentAddresses, params)));
     }
 
     /// @inheritdoc IUnlockCallback
@@ -34,13 +36,17 @@ abstract contract V4Router is IV4Router {
         SwapInfo memory swapInfo = abi.decode(encodedSwapInfo, (SwapInfo));
 
         if (swapInfo.swapType == SwapType.ExactInput) {
-            _swapExactInput(abi.decode(swapInfo.params, (IV4Router.ExactInputParams)), swapInfo.msgSender);
+            _swapExactInput(abi.decode(swapInfo.params, (IV4Router.ExactInputParams)), swapInfo.paymentAddresses);
         } else if (swapInfo.swapType == SwapType.ExactInputSingle) {
-            _swapExactInputSingle(abi.decode(swapInfo.params, (IV4Router.ExactInputSingleParams)), swapInfo.msgSender);
+            _swapExactInputSingle(
+                abi.decode(swapInfo.params, (IV4Router.ExactInputSingleParams)), swapInfo.paymentAddresses
+            );
         } else if (swapInfo.swapType == SwapType.ExactOutput) {
-            _swapExactOutput(abi.decode(swapInfo.params, (IV4Router.ExactOutputParams)), swapInfo.msgSender);
+            _swapExactOutput(abi.decode(swapInfo.params, (IV4Router.ExactOutputParams)), swapInfo.paymentAddresses);
         } else if (swapInfo.swapType == SwapType.ExactOutputSingle) {
-            _swapExactOutputSingle(abi.decode(swapInfo.params, (IV4Router.ExactOutputSingleParams)), swapInfo.msgSender);
+            _swapExactOutputSingle(
+                abi.decode(swapInfo.params, (IV4Router.ExactOutputSingleParams)), swapInfo.paymentAddresses
+            );
         } else {
             revert InvalidSwapType();
         }
@@ -48,20 +54,25 @@ abstract contract V4Router is IV4Router {
         return bytes("");
     }
 
-    function _swapExactInputSingle(IV4Router.ExactInputSingleParams memory params, address msgSender) private {
+    function _swapExactInputSingle(
+        IV4Router.ExactInputSingleParams memory params,
+        PaymentAddresses memory paymentAddresses
+    ) private {
         _swap(
             params.poolKey,
             params.zeroForOne,
             int256(-int128(params.amountIn)),
             params.sqrtPriceLimitX96,
-            msgSender,
+            paymentAddresses,
             true,
             true,
             params.hookData
         );
     }
 
-    function _swapExactInput(IV4Router.ExactInputParams memory params, address msgSender) private {
+    function _swapExactInput(IV4Router.ExactInputParams memory params, PaymentAddresses memory paymentAddresses)
+        private
+    {
         unchecked {
             uint256 pathLength = params.path.length;
             uint128 amountOut;
@@ -74,7 +85,7 @@ abstract contract V4Router is IV4Router {
                         zeroForOne,
                         int256(-int128(params.amountIn)),
                         0,
-                        msgSender,
+                        paymentAddresses,
                         i == 0,
                         i == pathLength - 1,
                         params.path[i].hookData
@@ -89,20 +100,25 @@ abstract contract V4Router is IV4Router {
         }
     }
 
-    function _swapExactOutputSingle(IV4Router.ExactOutputSingleParams memory params, address msgSender) private {
+    function _swapExactOutputSingle(
+        IV4Router.ExactOutputSingleParams memory params,
+        PaymentAddresses memory paymentAddresses
+    ) private {
         _swap(
             params.poolKey,
             params.zeroForOne,
             int256(int128(params.amountOut)),
             params.sqrtPriceLimitX96,
-            msgSender,
+            paymentAddresses,
             true,
             true,
             params.hookData
         );
     }
 
-    function _swapExactOutput(IV4Router.ExactOutputParams memory params, address msgSender) private {
+    function _swapExactOutput(IV4Router.ExactOutputParams memory params, PaymentAddresses memory paymentAddresses)
+        private
+    {
         unchecked {
             uint256 pathLength = params.path.length;
             uint128 amountIn;
@@ -116,7 +132,7 @@ abstract contract V4Router is IV4Router {
                         !oneForZero,
                         int256(int128(params.amountOut)),
                         0,
-                        msgSender,
+                        paymentAddresses,
                         i == 1,
                         i == pathLength,
                         params.path[i - 1].hookData
@@ -135,7 +151,7 @@ abstract contract V4Router is IV4Router {
         bool zeroForOne,
         int256 amountSpecified,
         uint160 sqrtPriceLimitX96,
-        address msgSender,
+        PaymentAddresses memory paymentAddresses,
         bool settle,
         bool take,
         bytes memory hookData
@@ -154,12 +170,12 @@ abstract contract V4Router is IV4Router {
 
         if (zeroForOne) {
             reciprocalAmount = amountSpecified < 0 ? delta.amount1() : delta.amount0();
-            if (settle) _payAndSettle(poolKey.currency0, msgSender, delta.amount0());
-            if (take) poolManager.take(poolKey.currency1, msgSender, uint128(delta.amount1()));
+            if (settle) _payAndSettle(poolKey.currency0, paymentAddresses.payer, delta.amount0());
+            if (take) poolManager.take(poolKey.currency1, paymentAddresses.recipient, uint128(delta.amount1()));
         } else {
             reciprocalAmount = amountSpecified < 0 ? delta.amount0() : delta.amount1();
-            if (settle) _payAndSettle(poolKey.currency1, msgSender, delta.amount1());
-            if (take) poolManager.take(poolKey.currency0, msgSender, uint128(delta.amount0()));
+            if (settle) _payAndSettle(poolKey.currency1, paymentAddresses.payer, delta.amount1());
+            if (take) poolManager.take(poolKey.currency0, paymentAddresses.recipient, uint128(delta.amount0()));
         }
     }
 
@@ -176,11 +192,11 @@ abstract contract V4Router is IV4Router {
         poolKey = PoolKey(currency0, currency1, params.fee, params.tickSpacing, params.hooks);
     }
 
-    function _payAndSettle(Currency currency, address msgSender, int128 settleAmount) private {
+    function _payAndSettle(Currency currency, address payer, int128 settleAmount) private {
         poolManager.sync(currency);
-        _pay(Currency.unwrap(currency), msgSender, address(poolManager), uint256(uint128(-settleAmount)));
+        _pay(Currency.unwrap(currency), payer, uint256(uint128(-settleAmount)));
         poolManager.settle(currency);
     }
 
-    function _pay(address token, address payer, address recipient, uint256 amount) internal virtual;
+    function _pay(address token, address payer, uint256 amount) internal virtual;
 }
diff --git a/contracts/interfaces/IV4Router.sol b/contracts/interfaces/IV4Router.sol
index 387e2ff0..d54000b6 100644
--- a/contracts/interfaces/IV4Router.sol
+++ b/contracts/interfaces/IV4Router.sol
@@ -21,14 +21,18 @@ interface IV4Router is IUnlockCallback {
 
     struct SwapInfo {
         SwapType swapType;
-        address msgSender;
+        PaymentAddresses paymentAddresses;
         bytes params;
     }
 
+    struct PaymentAddresses {
+        address payer;
+        address recipient;
+    }
+
     struct ExactInputSingleParams {
         PoolKey poolKey;
         bool zeroForOne;
-        address recipient;
         uint128 amountIn;
         uint128 amountOutMinimum;
         uint160 sqrtPriceLimitX96;
@@ -38,7 +42,6 @@ interface IV4Router is IUnlockCallback {
     struct ExactInputParams {
         Currency currencyIn;
         PathKey[] path;
-        address recipient;
         uint128 amountIn;
         uint128 amountOutMinimum;
     }
@@ -46,7 +49,6 @@ interface IV4Router is IUnlockCallback {
     struct ExactOutputSingleParams {
         PoolKey poolKey;
         bool zeroForOne;
-        address recipient;
         uint128 amountOut;
         uint128 amountInMaximum;
         uint160 sqrtPriceLimitX96;
@@ -56,7 +58,6 @@ interface IV4Router is IUnlockCallback {
     struct ExactOutputParams {
         Currency currencyOut;
         PathKey[] path;
-        address recipient;
         uint128 amountOut;
         uint128 amountInMaximum;
     }
diff --git a/test/V4Router.t.sol b/test/V4Router.t.sol
index 706d1712..97cf39d8 100644
--- a/test/V4Router.t.sol
+++ b/test/V4Router.t.sol
@@ -74,7 +74,7 @@ contract V4RouterTest is Test, Deployers, GasSnapshot {
         uint256 expectedAmountOut = 992054607780215625;
 
         IV4Router.ExactInputSingleParams memory params =
-            IV4Router.ExactInputSingleParams(key0, true, address(this), uint128(amountIn), 0, 0, bytes(""));
+            IV4Router.ExactInputSingleParams(key0, true, uint128(amountIn), 0, 0, bytes(""));
 
         uint256 prevBalance0 = key0.currency0.balanceOf(address(this));
         uint256 prevBalance1 = key0.currency1.balanceOf(address(this));
@@ -95,7 +95,7 @@ contract V4RouterTest is Test, Deployers, GasSnapshot {
         uint256 expectedAmountOut = 992054607780215625;
 
         IV4Router.ExactInputSingleParams memory params =
-            IV4Router.ExactInputSingleParams(key0, false, address(this), uint128(amountIn), 0, 0, bytes(""));
+            IV4Router.ExactInputSingleParams(key0, false, uint128(amountIn), 0, 0, bytes(""));
 
         uint256 prevBalance0 = key0.currency0.balanceOf(address(this));
         uint256 prevBalance1 = key0.currency1.balanceOf(address(this));
@@ -212,7 +212,7 @@ contract V4RouterTest is Test, Deployers, GasSnapshot {
         uint256 expectedAmountIn = 1008049273448486163;
 
         IV4Router.ExactOutputSingleParams memory params =
-            IV4Router.ExactOutputSingleParams(key0, true, address(this), uint128(amountOut), 0, 0, bytes(""));
+            IV4Router.ExactOutputSingleParams(key0, true, uint128(amountOut), 0, 0, bytes(""));
 
         uint256 prevBalance0 = key0.currency0.balanceOf(address(this));
         uint256 prevBalance1 = key0.currency1.balanceOf(address(this));
@@ -233,7 +233,7 @@ contract V4RouterTest is Test, Deployers, GasSnapshot {
         uint256 expectedAmountIn = 1008049273448486163;
 
         IV4Router.ExactOutputSingleParams memory params =
-            IV4Router.ExactOutputSingleParams(key0, false, address(this), uint128(amountOut), 0, 0, bytes(""));
+            IV4Router.ExactOutputSingleParams(key0, false, uint128(amountOut), 0, 0, bytes(""));
 
         uint256 prevBalance0 = key0.currency0.balanceOf(address(this));
         uint256 prevBalance1 = key0.currency1.balanceOf(address(this));
@@ -372,7 +372,7 @@ contract V4RouterTest is Test, Deployers, GasSnapshot {
 
     function getExactInputParams(MockERC20[] memory _tokenPath, uint256 amountIn)
         internal
-        view
+        pure
         returns (IV4Router.ExactInputParams memory params)
     {
         PathKey[] memory path = new PathKey[](_tokenPath.length - 1);
@@ -382,14 +382,13 @@ contract V4RouterTest is Test, Deployers, GasSnapshot {
 
         params.currencyIn = Currency.wrap(address(_tokenPath[0]));
         params.path = path;
-        params.recipient = address(this);
         params.amountIn = uint128(amountIn);
         params.amountOutMinimum = 0;
     }
 
     function getExactOutputParams(MockERC20[] memory _tokenPath, uint256 amountOut)
         internal
-        view
+        pure
         returns (IV4Router.ExactOutputParams memory params)
     {
         PathKey[] memory path = new PathKey[](_tokenPath.length - 1);
@@ -399,7 +398,6 @@ contract V4RouterTest is Test, Deployers, GasSnapshot {
 
         params.currencyOut = Currency.wrap(address(_tokenPath[_tokenPath.length - 1]));
         params.path = path;
-        params.recipient = address(this);
         params.amountOut = uint128(amountOut);
         params.amountInMaximum = type(uint128).max;
     }
diff --git a/test/shared/implementation/V4RouterImplementation.sol b/test/shared/implementation/V4RouterImplementation.sol
index aac7fde4..fada2418 100644
--- a/test/shared/implementation/V4RouterImplementation.sol
+++ b/test/shared/implementation/V4RouterImplementation.sol
@@ -10,10 +10,10 @@ contract V4RouterImplementation is V4Router {
     constructor(IPoolManager _poolManager) V4Router(_poolManager) {}
 
     function swap(IV4Router.SwapType swapType, bytes memory params) external {
-        _v4Swap(swapType, params);
+        _v4Swap(swapType, PaymentAddresses({payer: msg.sender, recipient: msg.sender}), params);
     }
 
-    function _pay(address token, address payer, address recipient, uint256 amount) internal override {
-        IERC20Minimal(token).transferFrom(payer, recipient, amount);
+    function _pay(address token, address payer, uint256 amount) internal override {
+        IERC20Minimal(token).transferFrom(payer, address(poolManager), amount);
     }
 }