diff --git a/gtk/gtkrender.c b/gtk/gtkrender.c
index 20c014d172..4f986bbf5a 100644
--- a/gtk/gtkrender.c
+++ b/gtk/gtkrender.c
@@ -1205,6 +1205,13 @@ gtk_render_icon_pixbuf (GtkStyleContext     *context,
  *
  * Renders the icon in @pixbuf at the specified @x and @y coordinates.
  *
+ * This function will render the icon in @pixbuf at exactly its size,
+ * regardless of scaling factors, which may not be appropriate when
+ * drawing on displays with high pixel densities.
+ *
+ * You probably want to use gtk_render_icon_surface() instead, if you
+ * already have a Cairo surface.
+ *
  * Since: 3.2
  **/
 void