-AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE")
-AC_DEFINE_UNQUOTED(VERSION, "$VERSION")
+ AC_CHECK_HEADERS(zlib.h gif_lib.h io.h wchar.h jpeglib.h assert.h signal.h pthread.h sys/stat.h sys/types.h dirent.h sys/bsdtypes.h sys/ndir.h sys/dir.h ndir.h time.h sys/time.h sys/resource.h)
+
+AC_DEFINE_UNQUOTED([PACKAGE], ["$PACKAGE"], [Name of package])
+AC_DEFINE_UNQUOTED([VERSION], ["$VERSION"], [Version number of package])