diff --git a/thor/fork_config.go b/thor/fork_config.go
index 15c60645c..449536c00 100644
--- a/thor/fork_config.go
+++ b/thor/fork_config.go
@@ -50,14 +50,14 @@ var forkConfigs = map[Bytes32]ForkConfig{
 		VIP191:    3337300,
 		ETH_CONST: 3337300,
 		BLOCKLIST: 4817300,
-		ETH_IST:   9180400, // ~UTC 2021-5-30 8:00
+		ETH_IST:   9254300, // ~ Mon, 07 Jun 2021 08:00:00 GMT
 	},
 	// testnet
 	MustParseBytes32("0x000000000b2bce3c70bc649a02749e8687721b09ed2e15997f466536b20bb127"): {
 		VIP191:    2898800,
 		ETH_CONST: 3192500,
 		BLOCKLIST: math.MaxUint32,
-		ETH_IST:   9141900, // ~UTC 2021-5-20 8:00
+		ETH_IST:   9146700, // ~ Thu, 20 May 2021 08:00:00 GMT
 	},
 }