diff --git a/core/genesis.go b/core/genesis.go
index d1ee1b6e92..8f71f9ef1e 100644
--- a/core/genesis.go
+++ b/core/genesis.go
@@ -464,8 +464,12 @@ func (g *Genesis) toBlockWithRoot(root common.Hash) *types.Block {
 	if g.GasLimit == 0 {
 		head.GasLimit = params.GenesisGasLimit
 	}
-	if g.Difficulty == nil && g.Mixhash == (common.Hash{}) {
-		head.Difficulty = params.GenesisDifficulty
+	if g.Difficulty == nil {
+		if g.Config != nil && g.Config.Ethash == nil {
+			head.Difficulty = big.NewInt(0)
+		} else if g.Mixhash == (common.Hash{}) {
+			head.Difficulty = params.GenesisDifficulty
+		}
 	}
 	if g.Config != nil && g.Config.IsLondon(common.Big0) {
 		if g.BaseFee != nil {
diff --git a/core/genesis_test.go b/core/genesis_test.go
index 3e120a9307..ad75afcd9e 100644
--- a/core/genesis_test.go
+++ b/core/genesis_test.go
@@ -44,14 +44,14 @@ func testSetupGenesis(t *testing.T, scheme string) {
 	var (
 		customghash = common.HexToHash("0x89c99d90b79719238d2645c7642f2c9295246e80775b38cfd162b696817fbd50")
 		customg     = Genesis{
-			Config: &params.ChainConfig{HomesteadBlock: big.NewInt(3)},
+			Config: &params.ChainConfig{HomesteadBlock: big.NewInt(3), Ethash: &params.EthashConfig{}},
 			Alloc: types.GenesisAlloc{
 				{1}: {Balance: big.NewInt(1), Storage: map[common.Hash]common.Hash{{1}: {1}}},
 			},
 		}
 		oldcustomg = customg
 	)
-	oldcustomg.Config = &params.ChainConfig{HomesteadBlock: big.NewInt(2)}
+	oldcustomg.Config = &params.ChainConfig{HomesteadBlock: big.NewInt(2), Ethash: &params.EthashConfig{}}
 
 	tests := []struct {
 		name           string