--- a/js/src/jsapi.cpp
+++ b/js/src/jsapi.cpp
@@ -5839,16 +5839,24 @@ JS_AtomizeAndPinStringN(JSContext* cx, c
     AssertHeapIsIdle();
     CHECK_REQUEST(cx);
     JSAtom* atom = Atomize(cx, s, length, PinAtom);
     MOZ_ASSERT_IF(atom, JS_StringHasBeenPinned(cx, atom));
     return atom;
 }
 
 JS_PUBLIC_API(JSString*)
+JS_NewLatin1String(JSContext* cx, JS::Latin1Char* chars, size_t length)
+{
+    AssertHeapIsIdle();
+    CHECK_REQUEST(cx);
+    return NewString<CanGC>(cx, chars, length);
+}
+
+JS_PUBLIC_API(JSString*)
 JS_NewUCString(JSContext* cx, char16_t* chars, size_t length)
 {
     AssertHeapIsIdle();
     CHECK_REQUEST(cx);
     return NewString<CanGC>(cx, chars, length);
 }
 
 JS_PUBLIC_API(JSString*)

--- a/js/src/jsapi.h
+++ b/js/src/jsapi.h
@@ -4718,16 +4718,19 @@ JS_AtomizeString(JSContext* cx, const ch
 
 extern JS_PUBLIC_API(JSString*)
 JS_AtomizeAndPinStringN(JSContext* cx, const char* s, size_t length);
 
 extern JS_PUBLIC_API(JSString*)
 JS_AtomizeAndPinString(JSContext* cx, const char* s);
 
 extern JS_PUBLIC_API(JSString*)
+JS_NewLatin1String(JSContext* cx, JS::Latin1Char* chars, size_t length);
+
+extern JS_PUBLIC_API(JSString*)
 JS_NewUCString(JSContext* cx, char16_t* chars, size_t length);
 
 extern JS_PUBLIC_API(JSString*)
 JS_NewUCStringCopyN(JSContext* cx, const char16_t* s, size_t n);
 
 extern JS_PUBLIC_API(JSString*)
 JS_NewUCStringCopyZ(JSContext* cx, const char16_t* s);