diff -Naur grsync-1.2.6.orig/src/callbacks.h grsync-1.2.6/src/callbacks.h
--- grsync-1.2.6.orig/src/callbacks.h	2013-04-30 13:48:54.000000000 +0200
+++ grsync-1.2.6/src/callbacks.h	2020-02-27 11:34:50.861824303 +0100
@@ -7,11 +7,11 @@
 #define ICON_PACKAGE PACKAGE_DATA_DIR "/" ICON_SOURCE
 #define ICON_PACKAGE_BUSY PACKAGE_DATA_DIR "/" ICON_SOURCE_BUSY
 
-GtkBuilder *builder;
-GtkWidget *main_window;
-gchar *argv_session, *argv_filename, *icon, *icon_busy;
-gboolean cmdline_session, cmdline_execute, cmdline_stayopen, cmdline_import;
-GtkListStore *liststore_session;
+extern GtkBuilder *builder;
+extern GtkWidget *main_window;
+extern gchar *argv_session, *argv_filename, *icon, *icon_busy;
+extern gboolean cmdline_session, cmdline_execute, cmdline_stayopen, cmdline_import;
+extern GtkListStore *liststore_session;
 
 void save_settings(gchar *session, gchar *filename);
 gboolean load_groups(gchar *session);
diff -Naur grsync-1.2.6.orig/src/main.c grsync-1.2.6/src/main.c
--- grsync-1.2.6.orig/src/main.c	2013-04-30 13:48:54.000000000 +0200
+++ grsync-1.2.6/src/main.c	2020-02-27 11:35:08.548834429 +0100
@@ -10,6 +10,12 @@
 #	include <libosso.h>
 #endif
 
+GtkBuilder *builder;
+GtkWidget *main_window;
+gchar *argv_session, *argv_filename, *icon, *icon_busy;
+gboolean cmdline_session, cmdline_execute, cmdline_stayopen, cmdline_import;
+GtkListStore *liststore_session;
+
 int main (int argc, char *argv[]) {
 #ifdef ENABLE_NLS
 	bindtextdomain(GETTEXT_PACKAGE, PACKAGE_LOCALE_DIR);