diff --git a/core/ledger/validator.go b/core/ledger/validator.go
index 0820f0da4..5910563ff 100644
--- a/core/ledger/validator.go
+++ b/core/ledger/validator.go
@@ -249,7 +249,7 @@ func TimestampCheck(timestamp int64) error {
 	latest := now.Add(TimestampTolerance)
 
 	if t.Before(earliest) || t.After(latest) {
-		return fmt.Errorf("timestamp %v exceed my tolerance [%v, %v]", t, earliest, latest)
+		return fmt.Errorf("timestamp %d exceed my tolerance [%d, %d]", timestamp, earliest.Unix(), latest.Unix())
 	}
 
 	return nil
diff --git a/nknd.go b/nknd.go
index df54bef7b..027786e47 100644
--- a/nknd.go
+++ b/nknd.go
@@ -37,7 +37,7 @@ import (
 )
 
 const (
-	TestNetVersionNum = 6
+	TestNetVersionNum = 7
 )
 
 var (