diff --git a/crypto/crypto.go b/crypto/crypto.go
index 9d6af6ea3c..7f7171f730 100644
--- a/crypto/crypto.go
+++ b/crypto/crypto.go
@@ -46,7 +46,7 @@ const DigestLength = 32
 
 var (
 	secp256k1N, _  = new(big.Int).SetString("fffffffffffffffffffffffffffffffebaaedce6af48a03bbfd25e8cd0364141", 16)
-	secp256k1halfN = new(big.Int).Rsh(secp256k1N, 1)
+	secp256k1halfN = new(big.Int).Div(secp256k1N, big.NewInt(2))
 )
 
 var errInvalidPubkey = errors.New("invalid secp256k1 public key")