-AC_CHECK_LIB(z, deflate, , AC_MSG_ERROR([*** must have zlib]))
-AC_CHECK_LIB(bz2, BZ2_bzWriteOpen, , AC_MSG_ERROR([*** must have bzlib]))
-AC_CHECK_LIB(gdbm, gdbm_open, , AC_MSG_ERROR([*** must have gdbm]))
+AC_CHECK_LIB(z, deflate, [:], AC_MSG_ERROR([*** must have zlib]))
+AC_CHECK_LIB(bz2, BZ2_bzWriteOpen, [:], AC_MSG_ERROR([*** must have bzlib]))
+AC_CHECK_LIB(gdbm, gdbm_open, [:], AC_MSG_ERROR([*** must have gdbm]))