diff --git a/glib/gsequence.c b/glib/gsequence.c
index 475990aed..3ed1eb801 100644
--- a/glib/gsequence.c
+++ b/glib/gsequence.c
@@ -1231,7 +1231,9 @@ g_sequence_set (GSequenceIter *iter,
  * g_sequence_get_length:
  * @seq: a #GSequence
  *
- * Returns the length of @seq
+ * Returns the length of @seq. Note that this method is O(h) where `h' is the
+ * height of the tree. It is thus more efficient to use g_sequence_is_empty()
+ * when comparing the length to zero.
  *
  * Returns: the length of @seq
  *