src/math/big/int_test.go | 20 ++++++++++++++++++++
 src/math/big/nat.go      |  4 ++--

diff --git a/src/math/big/int_test.go b/src/math/big/int_test.go
index b8e0778ca3201783a524a5c473754d74f94db946..4a4e548576777c3b7a6c5c148099172607394dab 100644
--- a/src/math/big/int_test.go
+++ b/src/math/big/int_test.go
@@ -1487,6 +1487,26 @@ 		t.Errorf("Sqrt(100) = %v, want 10 (aliased output)", r.Int64())
 	}
 }
 
+// We can't test this together with the other Exp tests above because
+// it requires a different receiver setup.
+func TestIssue22830(t *testing.T) {
+	one := new(Int).SetInt64(1)
+	base, _ := new(Int).SetString("84555555300000000000", 10)
+	mod, _ := new(Int).SetString("66666670001111111111", 10)
+	want, _ := new(Int).SetString("17888885298888888889", 10)
+
+	var tests = []int64{
+		0, 1, -1,
+	}
+
+	for _, n := range tests {
+		m := NewInt(n)
+		if got := m.Exp(base, one, mod); got.Cmp(want) != 0 {
+			t.Errorf("(%v).Exp(%s, 1, %s) = %s, want %s", n, base, mod, got, want)
+		}
+	}
+}
+
 func BenchmarkSqrt(b *testing.B) {
 	n, _ := new(Int).SetString("1"+strings.Repeat("0", 1001), 10)
 	b.ResetTimer()
diff --git a/src/math/big/nat.go b/src/math/big/nat.go
index 9b1a626c4cf18acd5d2df494bdc2ca740f13272e..607430064ccf2e3253e7a9fe92041fd6231e6035 100644
--- a/src/math/big/nat.go
+++ b/src/math/big/nat.go
@@ -575,8 +575,8 @@
 	// determine if z can be reused
 	// TODO(gri) should find a better solution - this if statement
 	//           is very costly (see e.g. time pidigits -s -n 10000)
-	if alias(z, uIn) || alias(z, v) {
-		z = nil // z is an alias for uIn or v - cannot reuse
+	if alias(z, u) || alias(z, uIn) || alias(z, v) {
+		z = nil // z is an alias for u or uIn or v - cannot reuse
 	}
 	q = z.make(m + 1)