diff --git a/builtin_math.go b/builtin_math.go
index 48f8e68..37f7d8c 100644
--- a/builtin_math.go
+++ b/builtin_math.go
@@ -110,7 +110,7 @@ func builtinMath_pow(call FunctionCall) Value {
 	// TODO Make sure this works according to the specification (15.8.2.13)
 	x := toFloat(call.Argument(0))
 	y := toFloat(call.Argument(1))
-	if x == 1 && math.IsInf(y, 0) {
+	if math.Abs(x) == 1 && math.IsInf(y, 0) {
 		return NaNValue()
 	}
 	return toValue_float64(math.Pow(x, y))
diff --git a/math_test.go b/math_test.go
index 2c4cdad..9b22807 100644
--- a/math_test.go
+++ b/math_test.go
@@ -220,6 +220,10 @@ func TestMath_pow(t *testing.T) {
 	test(`Math.pow(-0, -1)`, "-Infinity")
 	test(`Math.pow(-0, -2)`, "Infinity")
 	test(`Math.pow(-1, 0.1)`, "NaN")
+
+	test(`
+        [ Math.pow(-1, +Infinity), Math.pow(1, Infinity) ];
+    `, "NaN,NaN")
 }
 
 func TestMath_round(t *testing.T) {