--- a/pidgin/libpurple/protocols/facebook/mqtt.c
+++ b/pidgin/libpurple/protocols/facebook/mqtt.c
@@ -113,9 +113,9 @@
 	             G_SIGNAL_ACTION,
 	             0,
 	             NULL, NULL,
-	             fb_marshal_VOID__OBJECT,
+	             fb_marshal_VOID__POINTER,
 	             G_TYPE_NONE,
-	             1, G_TYPE_ERROR);
+	             1, G_TYPE_POINTER);
 
 	/**
 	 * FbMqtt::open:
