diff --git a/src/SimpleFunder.sol b/src/SimpleFunder.sol
index e74947fb..85f7e397 100644
--- a/src/SimpleFunder.sol
+++ b/src/SimpleFunder.sol
@@ -183,7 +183,7 @@ contract SimpleFunder is EIP712, Ownable, IFunder {
                 if gt(amount, allowance) {
                     mstore(m, 0x095ea7b3) // `approve(address,uint256)`.
                     mstore(add(m, 0x20), caller())
-                    mstore(add(m, 0x40), 0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF) // type(uint256).max
+                    mstore(add(m, 0x40), not(0)) // type(uint256).max
                     // Orchestrator checks for token transfer success, so we don't need to check it here.
                     pop(call(gas(), token, 0, add(m, 0x1c), 0x44, 0x00, 0x00))
                 }
diff --git a/test/SimpleFunder.t.sol b/test/SimpleFunder.t.sol
index b1c4608e..35988c3f 100644
--- a/test/SimpleFunder.t.sol
+++ b/test/SimpleFunder.t.sol
@@ -94,6 +94,19 @@ contract SimpleFunderTest is Test {
         assertGt(token.allowance(address(simpleFunder), orchestrator), allowanceBefore + 100 ether);
     }
 
+    function test_fund_setsMaxUint256Allowance() public {
+        ICommon.Transfer[] memory transfers = new ICommon.Transfer[](1);
+        transfers[0] = ICommon.Transfer({token: address(token), amount: 100 ether});
+
+        bytes32 digest = keccak256("test digest");
+        (uint8 v, bytes32 r, bytes32 s) = vm.sign(funderPrivateKey, digest);
+        bytes memory signature = abi.encodePacked(r, s, v);
+
+        simpleFunder.fund(digest, transfers, signature);
+
+        assertEq(token.allowance(address(simpleFunder), orchestrator), type(uint256).max);
+    }
+
     function test_fund_withInvalidSignature_reverts() public {
         ICommon.Transfer[] memory transfers = new ICommon.Transfer[](1);
         transfers[0] = ICommon.Transfer({token: address(token), amount: 100 ether});