diff --git a/script/Config.s.sol b/script/Config.s.sol
index ef34b6a..13ba006 100644
--- a/script/Config.s.sol
+++ b/script/Config.s.sol
@@ -3,9 +3,11 @@ pragma solidity ^0.8.20;
 
 // Generated by scripts/sync-config.py
 library Config {
-    address public constant ROUTER_MAINNET = 0x92e20164FC457a2aC35f53D06268168e6352b200;
-    address public constant ROUTER_SEPOLIA = 0xB587Bc36aaCf65962eCd6Ba59e2DA76f2f575408;
+    address public constant ROUTER_MAINNET = 0x4A73696ccF76E7381b044cB95127B3784369Ed63;
+    address public constant ROUTER_SEPOLIA = 0x24cD8b68aaC209217ff5a6ef1Bf55a59f2c8Ca6F;
     address public constant TREASURY = 0x598bF63F5449876efafa7b36b77Deb2070621C0E;
     address public constant USDC_MAINNET = 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913;
     address public constant USDC_SEPOLIA = 0xeAC1f2C7099CdaFfB91Aa3b8Ffd653Ef16935798;
+    uint256 public constant MIN_PAYMENT_AMOUNT = 1000;
+    uint256 public constant FEE_BPS = 100;
 }
diff --git a/script/DeploySepolia.s.sol b/script/DeploySepolia.s.sol
index efd4ec9..e913b4f 100644
--- a/script/DeploySepolia.s.sol
+++ b/script/DeploySepolia.s.sol
@@ -3,10 +3,11 @@ pragma solidity ^0.8.20;
 
 import {Script, console} from "forge-std/Script.sol";
 import {PayNodeRouter} from "../src/PayNodeRouter.sol";
+import {Config} from "./Config.s.sol";
 
 contract DeploySepolia is Script {
     function run() external {
-        address treasury = 0x598bF63F5449876efafa7b36b77Deb2070621C0E;
+        address treasury = Config.TREASURY;
 
         vm.startBroadcast();
         PayNodeRouter router = new PayNodeRouter(treasury);
diff --git a/src/PayNodeRouter.sol b/src/PayNodeRouter.sol
index 22582dc..cd79697 100644
--- a/src/PayNodeRouter.sol
+++ b/src/PayNodeRouter.sol
@@ -25,9 +25,11 @@ contract PayNodeRouter is Ownable2Step, Pausable {
     // Fixed protocol fee: 1% (100 basis points out of 10000)
     uint256 public constant PROTOCOL_FEE_BPS = 100;
     uint256 public constant MAX_BPS = 10000;
+    uint256 public constant MIN_PAYMENT_AMOUNT = 1000;
 
     error InvalidAddress();
-    error AmountMustBeGreaterThanZero();
+    error AmountTooLow();
+    error UnauthorizedCaller();
 
     // Redesigned event to match SDK requirements (indexed orderId, token verification, chainId)
     event PaymentReceived(
@@ -98,6 +100,8 @@ contract PayNodeRouter is Ownable2Step, Pausable {
         bytes32 r,
         bytes32 s
     ) external whenNotPaused {
+        if (msg.sender != payer) revert UnauthorizedCaller();
+
         // 1. Consume permit to grant allowance to this router
         IERC20Permit(token).permit(payer, address(this), amount, deadline, v, r, s);
 
@@ -110,7 +114,7 @@ contract PayNodeRouter is Ownable2Step, Pausable {
      */
     function _processPayment(address payer, address token, address merchant, uint256 amount, bytes32 orderId) internal {
         if (merchant == address(0) || token == address(0)) revert InvalidAddress();
-        if (amount == 0) revert AmountMustBeGreaterThanZero();
+        if (amount < MIN_PAYMENT_AMOUNT) revert AmountTooLow();
 
         // Calculate 1% fee
         uint256 fee = (amount * PROTOCOL_FEE_BPS) / MAX_BPS;
diff --git a/test/PayNodeRouter.t.sol b/test/PayNodeRouter.t.sol
index 7ed93bc..b62fb30 100644
--- a/test/PayNodeRouter.t.sol
+++ b/test/PayNodeRouter.t.sol
@@ -113,9 +113,8 @@ contract PayNodeRouterTest is Test {
         vm.expectEmit(true, true, true, true);
         emit PaymentReceived(orderId, merchant, payer, address(usdc), paymentAmount, expectedFee, block.chainid);
 
-        // We use an agent to send the transaction to test the Relayer functionality properly!
-        address agent = address(uint160(0x12345));
-        vm.prank(agent);
+        // Use the payer as the caller to prevent MiTM issues as per router security logic
+        vm.prank(payer);
         router.payWithPermit(payer, address(usdc), merchant, paymentAmount, orderId, deadline, v, r, s);
 
         assertEq(usdc.balanceOf(merchant), 99 * 10 ** 6);