diff --git a/gst/gstbus.c b/gst/gstbus.c
index effe84722d..df2351f3e9 100644
--- a/gst/gstbus.c
+++ b/gst/gstbus.c
@@ -762,7 +762,7 @@ no_replace:
 /**
  * gst_bus_get_pollfd:
  * @bus: A #GstBus
- * @fd: A GPollFD to fill
+ * @fd: (out): A GPollFD to fill
  *
  * Gets the file descriptor from the bus which can be used to get notified about
  * messages being available with functions like g_poll(), and allows integration