Hi, Prior to writing the report, I tried it with: AC_INIT([amhello], [1.0], [bug-automake@gnu.org]) AM_INIT_AUTOMAKE([-Wall -Werror foreign]) AC_PROG_CC AC_CONFIG_HEADERS([config.h]) AC_CONFIG_FILES( [Makefile] [src/Makefile:append/append.mk] ) AC_OUTPUT I have tried it once again and still receive the same error. Best Regards, Sean ________________________________ From: Hans-Bernhard Bröker Sent: Tuesday, August 8, 2017 2:19 AM To: Ghulam, Sean (Nokia - FI/Espoo); 28002@debbugs.gnu.org Subject: Re: bug#28002: automake prog_error when appending to configure.ac a colon-separated list of input files Am 07.08.2017 um 10:10 schrieb Ghulam, Sean (Nokia - FI/Espoo): > AC_CONFIG_FILES([ > Makefile> src/Makefile:append/append.mk> ]) Your bug report might be more convincing if you hadn't got that syntax wrong. Compare your example with the documentation example you found, and particularly note where the []s and are: > AC_CONFIG_FILES([Makefile:boiler/top.mk:boiler/bot.mk] > [lib/Makefile:boiler/lib.mk]) Wouldn't you agree that your example should have been AC_CONFIG_FILES( [Makefile] [src/Makefile:append/append.mk] ) ?