diff --git a/foundry/src/OneTransferFromOnly.sol b/foundry/src/OneTransferFromOnly.sol
index 072ac48..1a92344 100644
--- a/foundry/src/OneTransferFromOnly.sol
+++ b/foundry/src/OneTransferFromOnly.sol
@@ -5,24 +5,42 @@ import "@interfaces/IExecutor.sol";
 import "@openzeppelin/contracts/token/ERC20/utils/SafeERC20.sol";
 import "@permit2/src/interfaces/IAllowanceTransfer.sol";
 
-error TokenTransfer__AddressZero();
+error OneTransferFromOnly__AddressZero();
+error OneTransferFromOnly__MultipleTransferFrom();
 
+/**
+ * @title OneTransferFromOnly - Restrict to one transferFrom on approved params per swap
+ * @author PropellerHeads Devs
+ * @dev Restricts to one `transferFrom` (using `permit2` or regular `transferFrom`)
+ * per swap, while ensuring that the `transferFrom` is only performed on the input
+ * token and the input amount, from the msg.sender's wallet that calls the main swap
+ * method. Reverts if multiple `transferFrom`s are attempted.
+ */
 contract OneTransferFromOnly {
     using SafeERC20 for IERC20;
 
-    // this is a stupid name but the compiler was complaining that we already had a permit2 variable in TychoRouter
-    IAllowanceTransfer public immutable permit2lal;
-    uint256 private constant _TOKEN_IN_SLOT = 123;
-    uint256 private constant _AMOUNT_IN_SLOT = 124;
-    uint256 private constant _IS_PERMIT2_SLOT = 125;
-    uint256 private constant _SENDER_SLOT = 126;
-    uint256 private constant _IS_TRANSFER_EXECUTED_SLOT = 127;
+    IAllowanceTransfer public immutable permit2;
+    // keccak256("Dispatcher#TOKEN_IN_SLOT")
+    uint256 private constant _TOKEN_IN_SLOT =
+        0x66f353cfe8e3cbe0d03292348fbf0fca32e6e07fa0c2a52b4aac22193ac3b894;
+    // keccak256("Dispatcher#AMOUNT_IN_SLOT")
+    uint256 private constant _AMOUNT_IN_SLOT =
+        0x1f40aa2d23d66d03722685ce02e5d3a95545dfc8e7c56d1026790aa30be48937;
+    // keccak256("Dispatcher#IS_PERMIT2_SLOT")
+    uint256 private constant _IS_PERMIT2_SLOT =
+        0x3162c9d1175ca0ca7441f87984fdac41bbfdb13246f42c8bb4414d345da39e2a;
+    // keccak256("Dispatcher#SENDER_SLOT")
+    uint256 private constant _SENDER_SLOT =
+        0x5dcc7974be5cb30f183f878073999aaa6620995b9e052ab5a713071ff60ae9b5;
+    // keccak256("Dispatcher#IS_TRANSFER_EXECUTED_SLOT")
+    uint256 private constant _IS_TRANSFER_EXECUTED_SLOT =
+        0x1c64085c839fc2ff0f0aad20613eb6d056a1024e5990211e9eb30824dcd128c2;
 
     constructor(address _permit2) {
         if (_permit2 == address(0)) {
-            revert TokenTransfer__AddressZero();
+            revert OneTransferFromOnly__AddressZero();
         }
-        permit2lal = IAllowanceTransfer(_permit2);
+        permit2 = IAllowanceTransfer(_permit2);
     }
 
     // slither-disable-next-line assembly
@@ -56,12 +74,12 @@ contract OneTransferFromOnly {
             isTransferExecuted := tload(_IS_TRANSFER_EXECUTED_SLOT)
         }
         if (isTransferExecuted) {
-            return; // or revert?
+            revert OneTransferFromOnly__MultipleTransferFrom();
         }
 
         if (isPermit2) {
             // Permit2.permit is already called from the TychoRouter
-            permit2lal.transferFrom(sender, receiver, uint160(amount), tokenIn);
+            permit2.transferFrom(sender, receiver, uint160(amount), tokenIn);
             assembly {
                 tstore(_IS_TRANSFER_EXECUTED_SLOT, true)
             }
diff --git a/foundry/src/TychoRouter.sol b/foundry/src/TychoRouter.sol
index 538cc43..773e235 100644
--- a/foundry/src/TychoRouter.sol
+++ b/foundry/src/TychoRouter.sol
@@ -73,7 +73,6 @@ contract TychoRouter is
     ReentrancyGuard,
     OneTransferFromOnly
 {
-    IAllowanceTransfer public immutable permit2;
     IWETH private immutable _weth;
 
     using SafeERC20 for IERC20;