Hi, Fellippe. I don't have Windows 10 for test. Look in the SpriggsySprigs thread on Base64, below we started talking about this. Dav there gave a link to the old forum where the C source is upgraded. Try it with that. If that doesn't work, try shuffling the data types in the $ IF block. All you have to think about is the byte sum of the fields. If you replace _INTEGER64 with _OFFSET, the field length is the same (both take 8 bytes in a 64-bit system), if you replace LONG with _INTEGER64, you have an array 4 bytes longer, so you have to take 4 bytes again somewhere ( make it 4 bytes lower), otherwise it won't work.