Hi, the attached patch fixes a -Wundef warning when compiling the current svn version of libdvdread4 (as part of MPlayer) in the obvious way: $ make cc -MD -MP -Ilibdvdread4 -D_GNU_SOURCE -Ilibdvdcss -Wundef -Wall -Wno-switch -Wno-parentheses -Wpointer-arith -Wredundant-decls -Wstrict-prototypes -Wmissing-prototypes -Wdisabled-optimization -Wno-pointer-sign -Wdeclaration-after-statement -std=gnu99 -Werror-implicit-function-declaration -O4 -march=native -mtune=native -pipe -ffast-math -fomit-frame-pointer -fno-tree-vectorize -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -Ilibdvdread4 -I. -Iffmpeg -D_REENTRANT -I/usr/include/directfb -I/usr/include/ -D_REENTRANT -I/usr/include/freetype2 -I/usr/include/dirac -I/usr/include/schroedinger-1.0 -I/usr/include/orc-0.4 -c -o libdvdread4/dvd_reader.o libdvdread4/dvd_reader.c In file included from libdvdread4/dvd_reader.c:71:0: libdvdread4/md5.h:26:30: warning: "_LIBC" is not defined [-Wundef] cc -MD -MP -Ilibdvdread4 -D_GNU_SOURCE -Ilibdvdcss -Wundef -Wall -Wno-switch -Wno-parentheses -Wpointer-arith -Wredundant-decls -Wstrict-prototypes -Wmissing-prototypes -Wdisabled-optimization -Wno-pointer-sign -Wdeclaration-after-statement -std=gnu99 -Werror-implicit-function-declaration -O4 -march=native -mtune=native -pipe -ffast-math -fomit-frame-pointer -fno-tree-vectorize -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -Ilibdvdread4 -I. -Iffmpeg -D_REENTRANT -I/usr/include/directfb -I/usr/include/ -D_REENTRANT -I/usr/include/freetype2 -I/usr/include/dirac -I/usr/include/schroedinger-1.0 -I/usr/include/orc-0.4 -c -o libdvdread4/md5.o libdvdread4/md5.c In file included from libdvdread4/md5.c:28:0: libdvdread4/md5.h:26:30: warning: "_LIBC" is not defined [-Wundef] Please consider applying. Fix one warning every day. ;-) Thanks, Erik