diff --git a/control_dbus.h b/control_dbus.h
index 17e4dec..16661c9 100644
--- a/control_dbus.h
+++ b/control_dbus.h
@@ -2,6 +2,7 @@
 #define DBUS_CONTROL_H
 
 struct mbox_context;
+struct backend;
 
 int control_dbus_init(struct mbox_context *context);
 void control_dbus_free(struct mbox_context *context);
@@ -18,5 +19,6 @@
 int control_modified(struct mbox_context *context);
 int control_suspend(struct mbox_context *context);
 int control_resume(struct mbox_context *context, bool modified);
+int control_set_backend(struct mbox_context *context, struct backend *backend, void *data);
 
 #endif