From ff972aa398607b88fc4c54d3411800dcde180007 Mon Sep 17 00:00:00 2001
From: James Niken <155266991+dizer-ti@users.noreply.github.com>
Date: Mon, 17 Nov 2025 18:47:33 +0100
Subject: [PATCH] fix: correct error encoding for 4th byte in Base64 decode
 validation

---
 contracts/utils/Base64.sol | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contracts/utils/Base64.sol b/contracts/utils/Base64.sol
index 7c665c85f2e..b98efa7656d 100644
--- a/contracts/utils/Base64.sol
+++ b/contracts/utils/Base64.sol
@@ -208,7 +208,7 @@ library Base64 {
                 // slither-disable-next-line incorrect-shift
                 if iszero(and(shl(d, 1), 0xffffffd0ffffffc47ff5)) {
                     mstore(0, errorSelector)
-                    mstore(4, add(d, 43))
+                    mstore(4, shl(248, add(d, 43)))
                     revert(0, 0x24)
                 }