--- a/js/public/Id.h
+++ b/js/public/Id.h
@@ -64,22 +64,16 @@ JSID_TO_STRING(jsid id)
  *
  * N.B. if a jsid is backed by a string which has not been interned, that
  * string must be appropriately rooted to avoid being collected by the GC.
  */
 JS_PUBLIC_API(jsid)
 INTERNED_STRING_TO_JSID(JSContext* cx, JSString* str);
 
 static MOZ_ALWAYS_INLINE bool
-JSID_IS_ZERO(jsid id)
-{
-    return JSID_BITS(id) == 0;
-}
-
-static MOZ_ALWAYS_INLINE bool
 JSID_IS_INT(jsid id)
 {
     return !!(JSID_BITS(id) & JSID_TYPE_INT);
 }
 
 static MOZ_ALWAYS_INLINE int32_t
 JSID_TO_INT(jsid id)
 {