diff --git a/core/genesis.go b/core/genesis.go
index 4949197da5cd..633b2daf74b9 100644
--- a/core/genesis.go
+++ b/core/genesis.go
@@ -397,7 +397,7 @@ 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")
 	}
 	if err := g.Alloc.write(db, block.Hash()); err != nil {