diff --git a/builtin_date.go b/builtin_date.go
index a5cb2da..cf67009 100644
--- a/builtin_date.go
+++ b/builtin_date.go
@@ -30,6 +30,14 @@ func builtinDate_toUTCString(call FunctionCall) Value {
 	return toValue(date.Time().Format(time_.RFC1123))
 }
 
+func builtinDate_toGMTString(call FunctionCall) Value {
+	date := dateObjectOf(call.thisObject())
+	if date.isNaN {
+		return toValue("Invalid Date")
+	}
+	return toValue(date.Time().Format("Mon, 02 Jan 2006 15:04:05 GMT"))
+}
+
 func builtinDate_getTime(call FunctionCall) Value {
 	date := dateObjectOf(call.thisObject())
 	if date.isNaN {
diff --git a/date_test.go b/date_test.go
index 8b93d31..30e663f 100644
--- a/date_test.go
+++ b/date_test.go
@@ -19,6 +19,7 @@ func TestDate(t *testing.T) {
 
 	test(`Date`, "[function]")
 	test(`new Date(0).toUTCString()`, "Thu, 01 Jan 1970 00:00:00 UTC")
+	test(`new Date(0).toGMTString()`, "Thu, 01 Jan 1970 00:00:00 GMT")
 	if false {
 		// TODO
 		test(`new Date(0).toLocaleString()`, "")
diff --git a/global.go b/global.go
index fab0c4a..091c79a 100644
--- a/global.go
+++ b/global.go
@@ -348,6 +348,7 @@ func newContext() *_runtime {
 		self.Global.DatePrototype,
 		"toString", 0, builtinDate_toString,
 		"toUTCString", 0, builtinDate_toUTCString,
+		"toGMTString", 0, builtinDate_toGMTString,
 		"toLocaleString", 0, builtinDate_toLocaleString,
 		"toLocaleDateString", 0, builtinDate_toLocaleDateString,
 		"toLocaleTimeString", 0, builtinDate_toLocaleTimeString,