OK, Eily has provided the solution, but I don't understand why you use such a strange-looking reegex: 
/^(.{36})(.*?)\0\0\0/

[download]
Why do you have 36 times any char, followed by the smallest number of any characters still making the rest of the match possible?

In reply to Re: Regex trouble w/ embedded 0s? by Laurent_R
in thread Regex trouble w/ embedded 0s? by roboticus

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