diff --git a/core/blockchain.go b/core/blockchain.go
index 906f70b190b2..096517f2db33 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -893,7 +893,7 @@ func (bc *BlockChain) WriteBlockWithState(block *types.Block, receipts []*types.
 
 	currentBlock := bc.CurrentBlock()
 	//localTd := bc.GetTd(currentBlock.Hash(), currentBlock.NumberU64())
-	//externTd := new(big.Int).Add(block.Difficulty(), ptd)
+	externTd := new(big.Int).Add(block.Difficulty(), ptd)
 
 	// Irrelevant of the canonical status, write the block itself to the database
 	if err := bc.hc.WriteTd(block.Hash(), block.NumberU64(), externTd); err != nil {