diff --git a/blockchain/validate.go b/blockchain/validate.go
index 85946611..8f32842b 100644
--- a/blockchain/validate.go
+++ b/blockchain/validate.go
@@ -547,7 +547,7 @@ func checkBlockSanity(block *btcutil.Block, powLimit *big.Int, timeSource Median
 	// Do some preliminary checks on each transaction to ensure they are
 	// sane before continuing.
 	for _, tx := range transactions {
-		err := CheckTransactionSanity(tx, false)
+		err := CheckTransactionSanity(tx, block.Height() >= param.ActiveParams.GrandForkHeight)
 		if err != nil {
 			return err
 		}