diff --git a/bn256_test.go b/bn256_test.go
index f630019..b7e1030 100644
--- a/bn256_test.go
+++ b/bn256_test.go
@@ -1,6 +1,7 @@
 package bn256
 
 import (
+	"math/big"
 	"testing"
 
 	"bytes"
@@ -210,6 +211,29 @@ func TestDirtyUnmarshal(t *testing.T) {
 	}
 }
 
+// TestPairNegativeG2 tests that e(g1, -g2) + e(-g1, g2) = O.
+// It is based on py_ecc:
+// https://github.com/ethereum/py_ecc/blob/v8.0.0/tests/core/test_bn128_and_bls12_381.py#L296
+func TestPairNegativeG2(t *testing.T) {
+	g1Inf := new(G1).ScalarBaseMult(Order)
+	g2Inf := new(G2).ScalarBaseMult(Order)
+	gTInf := Pair(g1Inf, g2Inf)
+
+	g1 := new(G1).ScalarBaseMult(big.NewInt(1))
+	g2 := new(G2).ScalarBaseMult(big.NewInt(1))
+	p1 := Pair(g1, g2)
+	pn1 := Pair(new(G1).Neg(g1), g2)
+	np1 := Pair(g1, new(G2).Neg(g2))
+
+	p1np1 := new(GT).Add(p1, np1)
+	if !bytes.Equal(p1np1.Marshal(), gTInf.Marshal()) {
+		t.Errorf("p1 * np1 = %v want %v", p1np1, gTInf)
+	}
+	if !bytes.Equal(pn1.Marshal(), np1.Marshal()) {
+		t.Errorf("e(-G1, G2) != e(G1, -G2)")
+	}
+}
+
 func BenchmarkG1(b *testing.B) {
 	x, _ := rand.Int(rand.Reader, Order)
 	b.ResetTimer()
diff --git a/twist.go b/twist.go
index 18d18d1..52cee88 100644
--- a/twist.go
+++ b/twist.go
@@ -195,5 +195,5 @@ func (c *twistPoint) Neg(a *twistPoint) {
 	c.x.Set(&a.x)
 	c.y.Neg(&a.y)
 	c.z.Set(&a.z)
-	c.t.SetZero()
+	c.t.Set(&a.t)
 }