diff --git a/btcec/signature.go b/btcec/signature.go
index a4781b00f..bddb22831 100644
--- a/btcec/signature.go
+++ b/btcec/signature.go
@@ -427,9 +427,7 @@ func signRFC6979(privateKey *PrivateKey, hash []byte) (*Signature, error) {
 	k := nonceRFC6979(privkey.D, hash)
 	inv := new(big.Int).ModInverse(k, N)
 	r, _ := privkey.Curve.ScalarBaseMult(k.Bytes())
-	if r.Cmp(N) == 1 {
-		r.Sub(r, N)
-	}
+	r.Mod(r, N)
 
 	if r.Sign() == 0 {
 		return nil, errors.New("calculated R is zero")