diff --git a/core/genesis.go b/core/genesis.go
index 1d17f298a4fb..8fd96b2507bf 100644
--- a/core/genesis.go
+++ b/core/genesis.go
@@ -324,7 +324,7 @@ func (g *Genesis) Commit(db ethdb.Database) (*types.Block, error) {
 	if err := config.CheckConfigForkOrder(); err != nil {
 		return nil, err
 	}
-	if config.Clique != nil && len(block.Extra()) == 0 {
+	if config.Clique != nil && len(block.Extra()) < 32+crypto.SignatureLength {
 		return nil, errors.New("can't start clique chain without signers")
 	}
 	rawdb.WriteTd(db, block.Hash(), block.NumberU64(), block.Difficulty())