diff --git a/les/backend.go b/les/backend.go
index a3474a6830..d9ecd7345c 100644
--- a/les/backend.go
+++ b/les/backend.go
@@ -82,7 +82,7 @@ func New(ctx *node.ServiceContext, config *eth.Config) (*LightEthereum, error) {
 	if err != nil {
 		return nil, err
 	}
-	chainConfig, genesisHash, genesisErr := core.SetupGenesisBlock(chainDb, config.Genesis)
+	chainConfig, genesisHash, genesisErr := core.SetupGenesisBlockWithOverride(chainDb, config.Genesis, config.ConstantinopleOoverride)
 	if _, isCompat := genesisErr.(*params.ConfigCompatError); genesisErr != nil && !isCompat {
 		return nil, genesisErr
 	}