diff --git a/configure.ac b/configure.ac
--- a/configure.ac
+++ b/configure.ac
# Checks for libraries.
# Checks for header files.
-AC_CHECK_HEADERS([stdio.h stdlib.h string.h math.h float.h ctype.h libgen.h dirent.h])
+AC_CHECK_HEADERS([string.h math.h float.h ctype.h libgen.h dirent.h])
# Checks for typedefs, structures, and compiler characteristics.
+
# Checks for library functions.
AC_FUNC_MALLOC
LIBS="$LIBS -L/usr/lib64 -L/usr/lib -lm -ljpeg -lcfitsio"
-CFLAGS="-ansi $CFLAGS -I/usr/include -I/usr/include/cfitsio"
+CFLAGS="-ansi -Wall $CFLAGS -I/usr/include -I/usr/include/cfitsio"
#---------------------------------------------------------------------#
# Now we check for cfitsio headers and library #
#---------------------------------------------------------------------#