diff --git a/glib/gdataset.c b/glib/gdataset.c
index fb6cba5b6..d3c1cbd1f 100644
--- a/glib/gdataset.c
+++ b/glib/gdataset.c
@@ -801,6 +801,7 @@ g_datalist_id_get_data (GData  **datalist,
 /**
  * GDuplicateFunc:
  * @data: the data to duplicate
+ * @user_data: user data that was specified in g_datalist_id_dup_data()
  *
  * The type of functions that are used to 'duplicate' an object.
  * What this means depends on the context, it could just be
diff --git a/glib/gdataset.h b/glib/gdataset.h
index 123797bc1..a93f6ae99 100644
--- a/glib/gdataset.h
+++ b/glib/gdataset.h
@@ -55,12 +55,12 @@ void     g_datalist_id_set_data_full    (GData            **datalist,
 typedef gpointer (*GDuplicateFunc) (gpointer data, gpointer user_data);
 
 GLIB_AVAILABLE_IN_2_34
-gpointer g_datalist_id_dup_data         (GData            **data,
+gpointer g_datalist_id_dup_data         (GData            **datalist,
                                          GQuark             key_id,
                                          GDuplicateFunc     dup_func,
 					 gpointer           user_data);
 GLIB_AVAILABLE_IN_2_34
-gboolean g_datalist_id_replace_data     (GData            **data,
+gboolean g_datalist_id_replace_data     (GData            **datalist,
                                          GQuark             key_id,
                                          gpointer           oldval,
                                          gpointer           newval,