diff --git a/acconfig.h b/acconfig.h
index 42322e7fd..6c4713eed 100644
--- a/acconfig.h
+++ b/acconfig.h
@@ -9,6 +9,12 @@
 #undef HAVE_U_INT32_T
 #undef HAVE_U_INT64_T
 
+/* Define this if your `struct tm' has a field `tm_gmtoff' */
+#undef HAVE_STRUCT_TM_TM_GMTOFF
+
+/* Define this if you have a variable `timezone' */
+#undef HAVE_TIMEZONE
+
 #undef VOID_RETSIGTYPE
 
 #ifdef VOID_RETSIGTYPE