diff --git a/src/openvpn/options.c b/src/openvpn/options.c
index 6f6eb73d..26eac836 100644
--- a/src/openvpn/options.c
+++ b/src/openvpn/options.c
@@ -3278,6 +3278,12 @@ options_postprocess_mutate(struct options *o)
      * when using --pull
      */
     pre_connect_save(o);
+
+    /* Give a general warning at the end of initialisation that defaults
+     * have changed */
+    msg(M_WARN, "Note that modernisation of defaults in OpenVPN 2.6 limits "
+                "compatibility with old versions. See Changes.rst and "
+                "--compat-mode in the manual for details.");
 }
 
 /*