--- a/Helpviewer/FlashCookieManager/FlashCookieReader.py	Mon Apr 11 20:10:03 2016 +0200
+++ b/Helpviewer/FlashCookieManager/FlashCookieReader.py	Tue Apr 12 18:43:57 2016 +0200
@@ -104,6 +104,8 @@
         self.__data.seek(0)
         self.__data.read(2)
         sLenData = self.__data.read(4)
+        if len(sLenData) != 4:
+            raise FlashCookieReaderError("Flash cookie is invalid.")
         lenData, = struct.unpack(">L", sLenData)    # unsigned long, big-endian
         if lenSolData != lenData + 6:
             raise FlashCookieReaderError(