diff --git a/.env.example b/.env.example
index bd17dfb..3c9a120 100644
--- a/.env.example
+++ b/.env.example
@@ -4,4 +4,7 @@ export ETH_NODE_URI="http://localhost:8545"
 # export ETH_NODE_BACKUP_URI="https://mainnet.infura.io/v3/API_KEY" # optional
 
 # Beacon node is required for bid collection
-# export BEACON_URI="http://localhost:3500"
\ No newline at end of file
+# export BEACON_URI="http://localhost:3500"
+
+# Genesis time is used to calculate slot numbers, if use devnet/custom chain, set this
+# export GENESIS="1606824023"
diff --git a/vars/vars.go b/vars/vars.go
index 5fe34a9..6e651d6 100644
--- a/vars/vars.go
+++ b/vars/vars.go
@@ -4,6 +4,8 @@ package vars
 import (
 	"os"
 
+	"github.com/flashbots/go-utils/cli"
+
 	relaycommon "github.com/flashbots/mev-boost-relay/common"
 )
 
@@ -11,7 +13,7 @@ var (
 	Version  = "dev" // is set during build process
 	LogDebug = os.Getenv("DEBUG") != ""
 	LogJSON  = os.Getenv("LOG_JSON") != ""
-	Genesis  = 1_606_824_023
+	Genesis  = cli.GetEnvInt("GENESIS", 1_606_824_023)
 
 	DefaultBeaconURI        = relaycommon.GetEnv("BEACON_URI", "http://localhost:3500")
 	DefaultPostgresDSN      = relaycommon.GetEnv("POSTGRES_DSN", "postgres://postgres:postgres@localhost:5432/postgres?sslmode=disable")