--- a/js/src/jsdate.cpp
+++ b/js/src/jsdate.cpp
@@ -870,17 +870,17 @@ ParseISOStyleDate(const CharT* s, size_t
         isLocalTime = true;
     }
 
  done:
     if (year > 275943 // ceil(1e8/365) + 1970
         || (month == 0 || month > 12)
         || (day == 0 || day > size_t(DaysInMonth(year,month)))
         || hour > 24
-        || ((hour == 24) && (min > 0 || sec > 0))
+        || ((hour == 24) && (min > 0 || sec > 0 || frac > 0))
         || min > 59
         || sec > 59
         || tzHour > 23
         || tzMin > 59)
     {
         return false;
     }