diff --git a/src/SignatureChecker.sol b/src/SignatureChecker.sol
index 2f8051e..f38f740 100644
--- a/src/SignatureChecker.sol
+++ b/src/SignatureChecker.sol
@@ -10,7 +10,7 @@ contract SignatureChecker is Ownable {
     mapping(address => bool) public isNotary;
 
     /// valid digests for a given address
-    mapping(address => bytes32) public digests;
+    mapping(bytes32 => address) public digests;
 
     /// @notice Error for invalid signatures
     error InvalidSignature();
@@ -80,11 +80,13 @@ contract SignatureChecker is Ownable {
         if (recoveredSigner != signer) {
             revert InvalidSignature();
         }
-        if (digests[msg.sender] == digest) {
+
+        // TODO(WJ 2025-02-20): Should check for any sender.
+        if (digests[digest] == msg.sender) {
             revert DuplicateProof();
         }
 
-        digests[msg.sender] = digest;
+        digests[digest] = msg.sender;
         return true;
     }
 }
diff --git a/test/SignatureChecker.t.sol b/test/SignatureChecker.t.sol
index 0c6744e..28fd08b 100644
--- a/test/SignatureChecker.t.sol
+++ b/test/SignatureChecker.t.sol
@@ -11,7 +11,7 @@ contract SignatureCheckerTest is Test {
         signatureChecker = new SignatureChecker(0xfdf07A5dCfa7b74f4c28DAb23eaD8B1c43Be801F);
     }
 
-    function test_isValidSignatureNow() public {
+    function test_isValidSignature() public {
         // TEST vector from web-prover @ githash 2dc768e818d6f9fef575a88a2ceb80c0ed11974f
         address signer = 0xfdf07A5dCfa7b74f4c28DAb23eaD8B1c43Be801F;
         bytes32 digest = bytes32(0xe45537be7b5cd288c9c46b7e027b4f5a66202146012f792c1b1cabb65828994b);