diff --git a/library.c b/library.c
index 731a457b..c03f5608 100644
--- a/library.c
+++ b/library.c
@@ -91,6 +91,8 @@ struct openconnect_info *openconnect_vpninfo_new(const char *useragent,
 	bindtextdomain("openconnect", LOCALEDIR);
 #endif
 
+	vpninfo->proto.vpn_close_session = cstp_bye;
+
 	return vpninfo;
 
 err:
diff --git a/mainloop.c b/mainloop.c
index 3ce2148b..6f563706 100644
--- a/mainloop.c
+++ b/mainloop.c
@@ -224,8 +224,8 @@ int openconnect_mainloop(struct openconnect_info *vpninfo,
 #endif
 	}
 
-	if (vpninfo->quit_reason)
-		cstp_bye(vpninfo, vpninfo->quit_reason);
+	if (vpninfo->quit_reason && vpninfo->proto.vpn_close_session)
+		vpninfo->proto.vpn_close_session(vpninfo, vpninfo->quit_reason);
 
 	os_shutdown_tun(vpninfo);
 	return ret < 0 ? ret : -EIO;
diff --git a/openconnect-internal.h b/openconnect-internal.h
index 835bd6f0..c83eb2b3 100644
--- a/openconnect-internal.h
+++ b/openconnect-internal.h
@@ -201,7 +201,13 @@ struct proxy_auth_state {
 	char *challenge;
 };
 
+struct vpn_proto {
+	int (*vpn_close_session)(struct openconnect_info *vpninfo, const char *reason);
+};
+
 struct openconnect_info {
+	struct vpn_proto proto;
+
 #ifdef HAVE_ICONV
 	iconv_t ic_legacy_to_utf8;
 	iconv_t ic_utf8_to_legacy;