The otp_src_R12B-5_OTP-7738.patch fixes the following issue present in otp_src_R12B-5: OTP-7738 A process being garbage collected via the garbage_collect/1 BIF or the check_process_code/2 BIF didn't handle message receive and resume correctly during the garbage collect. When this occurred, the process returned to the state it had before the garbage collect instead of entering the new state. You need to apply the patch with a gnu patch compatible patch program. How to apply the patch: $ ls otp_src_R12B-5_OTP-7738.patch otp_src_R12B-5.tar.gz $ gtar -zxf otp_src_R12B-5.tar.gz $ patch -ZNp0 < otp_src_R12B-5_OTP-7738.patch patching file otp_src_R12B-5/erts/emulator/beam/erl_gc.c patching file otp_src_R12B-5/erts/emulator/beam/erl_message.c patching file otp_src_R12B-5/erts/emulator/beam/erl_process.c patching file otp_src_R12B-5/erts/emulator/beam/erl_process.h $ cd otp_src_R12B-5 $ # configure, make, and make install as usual...