diff --git a/glib/gtimezone.c b/glib/gtimezone.c
index 00492995c..72e6830ac 100644
--- a/glib/gtimezone.c
+++ b/glib/gtimezone.c
@@ -2223,7 +2223,7 @@ interval_valid (GTimeZone *tz,
  * g_time_zone_adjust_time:
  * @tz: a #GTimeZone
  * @type: the #GTimeType of @time_
- * @time_: a pointer to a number of seconds since January 1, 1970
+ * @time_: (inout): a pointer to a number of seconds since January 1, 1970
  *
  * Finds an interval within @tz that corresponds to the given @time_,
  * possibly adjusting @time_ if required to fit into an interval.