diff --git a/gdk-pixbuf/gdk-pixbuf-scale.c b/gdk-pixbuf/gdk-pixbuf-scale.c
index acfe874cab..efb07b7ef8 100644
--- a/gdk-pixbuf/gdk-pixbuf-scale.c
+++ b/gdk-pixbuf/gdk-pixbuf-scale.c
@@ -52,6 +52,10 @@
  * Try to use gdk_pixbuf_scale_simple() first, this function is
  * the industrial-strength power tool you can fall back to if
  * gdk_pixbuf_scale_simple() isn't powerful enough.
+ *
+ * If the source rectangle overlaps the destination rectangle on the
+ * same pixbuf, it will be overwritten during the scaling which
+ * results in rendering artifacts.
  **/
 void
 gdk_pixbuf_scale (const GdkPixbuf *src,
diff --git a/gdk-pixbuf/gdk-pixbuf-util.c b/gdk-pixbuf/gdk-pixbuf-util.c
index aeee33dbee..1b0de51f35 100644
--- a/gdk-pixbuf/gdk-pixbuf-util.c
+++ b/gdk-pixbuf/gdk-pixbuf-util.c
@@ -119,6 +119,10 @@ gdk_pixbuf_add_alpha (const GdkPixbuf *pixbuf,
  *
  * Copies a rectangular area from @src_pixbuf to @dest_pixbuf.  Conversion of
  * pixbuf formats is done automatically.
+ *
+ * If the source rectangle overlaps the destination rectangle on the
+ * same pixbuf, it will be overwritten during the copy operation.
+ * Therefore, you can not use this function to scroll a pixbuf.
  **/
 void
 gdk_pixbuf_copy_area (const GdkPixbuf *src_pixbuf,