The Mac OS X version of KS 1.1 has a bug where the game crashes on reaching the Act 1 bad end in French. This is a patch to fix it:
http://dl.katawa-shoujo.com/gold_1.1/[4ls]_katawa_shoujo_1.1.1_patch_[mac][E4951D8E].zip
Again, this patch ONLY applies to the OS X version of 1.1, it is not necessary for any other version (or if you do not intend to ever read it in French).
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