-AC_CHECK_LIB(gmp, mpf_get_str, [LIBS="-lgmp $LIBS"],
- [AC_CHECK_LIB(gmp, __gmpf_get_str, [LIBS="-lgmp $LIBS"])])
+AC_CHECK_LIB(gmp, mpf_get_str,,
+ AC_CHECK_LIB(gmp, __gmpf_get_str,,
+ AC_MSG_ERROR([You must install libgmp])
+ )
+)
+
+AC_CHECK_FUNC(getopt_long,,
+ AC_MSG_ERROR(`This application depends upon getopt_long'))
+