From cf8cca17ef5714c7e4e7641d3db5147ea6c76071 Mon Sep 17 00:00:00 2001
From: Leo <leonard.paturel@openzeppelin.com>
Date: Fri, 8 Aug 2025 21:34:05 +0200
Subject: [PATCH] prevents underflow

---
 src/protocol/taiko_alethia/TaikoInbox.sol | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/protocol/taiko_alethia/TaikoInbox.sol b/src/protocol/taiko_alethia/TaikoInbox.sol
index 1ea46316..9ef0dabd 100644
--- a/src/protocol/taiko_alethia/TaikoInbox.sol
+++ b/src/protocol/taiko_alethia/TaikoInbox.sol
@@ -66,8 +66,7 @@ contract TaikoInbox is IInbox, DelayedInclusionStore, Ownable {
             require(lookahead.isCurrentPreconfer(msg.sender), NotCurrentPreconfer());
         }
 
-        // Build the attribute for the anchor transaction inputs
-        require(anchorBlockId >= block.number - maxAnchorBlockIdOffset, AnchorBlockTooOld());
+        require(anchorBlockId + maxAnchorBlockIdOffset >= block.number, AnchorBlockTooOld());
 
         Metadata memory metadata = Metadata({
             anchorBlockId: anchorBlockId,