diff --git a/tests/difficulty_test_util.go b/tests/difficulty_test_util.go
index b012b370fe..9ef1503aff 100644
--- a/tests/difficulty_test_util.go
+++ b/tests/difficulty_test_util.go
@@ -24,7 +24,7 @@ import (
 	"github.com/ubiq/go-ubiq/common"
 	"github.com/ubiq/go-ubiq/common/math"
 	"github.com/ubiq/go-ubiq/consensus/ubqhash"
-	"github.com/ubiq/go-ubiq/core/types"
+	//"github.com/ubiq/go-ubiq/core/types"
 	"github.com/ubiq/go-ubiq/params"
 )
 
@@ -50,14 +50,14 @@ type difficultyTestMarshaling struct {
 
 func (test *DifficultyTest) Run(config *params.ChainConfig) error {
 	parentNumber := big.NewInt(int64(test.CurrentBlockNumber - 1))
-	parent := &types.Header{
+	/*parent := &types.Header{
 		Difficulty: test.ParentDifficulty,
 		Time:       test.ParentTimestamp,
 		Number:     parentNumber,
 		UncleHash:  test.UncleHash,
-	}
+	}*/
 
-	actual := ubqhash.CalcDifficulty(config, test.CurrentTimestamp.Uint64(), parent)
+	actual := ubqhash.CalcDifficultyLegacy(test.CurrentTimestamp.Uint64(), test.ParentTimestamp.Uint64(), parentNumber, test.ParentDifficulty)
 	exp := test.CurrentDifficulty
 
 	if actual.Cmp(exp) != 0 {