From 3ba522aba1c47a5793343c13f637417fa971a59d Mon Sep 17 00:00:00 2001
From: Shane Bammel <sjb933@gmail.com>
Date: Mon, 3 Oct 2022 22:35:48 -0500
Subject: [PATCH] Allow mismatching EIP158 ChainID if at fork

---
 params/config.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/params/config.go b/params/config.go
index 0533c7599..f3a239e7a 100644
--- a/params/config.go
+++ b/params/config.go
@@ -700,7 +700,8 @@ func (c *ChainConfig) checkCompatible(newcfg *ChainConfig, headNumber *big.Int,
 	if isForkBlockIncompatible(c.EIP158Block, newcfg.EIP158Block, headNumber) {
 		return newBlockCompatError("EIP158 fork block", c.EIP158Block, newcfg.EIP158Block)
 	}
-	if c.IsEIP158(headNumber) && !configBlockEqual(c.ChainID, newcfg.ChainID) {
+	// allow mismatching ChainID if we're at the PrimordialPulseBlock
+	if c.IsEIP158(headNumber) && !configBlockEqual(c.ChainID, newcfg.ChainID) && !newcfg.IsPrimordialPulseBlock(new(big.Int).Add(headNumber, common.Big1)) {
 		return newBlockCompatError("EIP158 chain ID", c.EIP158Block, newcfg.EIP158Block)
 	}
 	if isForkBlockIncompatible(c.ByzantiumBlock, newcfg.ByzantiumBlock, headNumber) {