diff --git a/ChangeLog b/ChangeLog
index c1512525df..d229849dda 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2007-04-26  Sven Neumann  <sven@gimp.org>
+
+	* libgimp/gimp.c: document the image_types parameter (bug #326988).
+
 2007-04-26  Sven Neumann  <sven@gimp.org>
 
 	* app/paint-funcs/paint-funcs.c (gaussian_blur_region)
diff --git a/libgimp/gimp.c b/libgimp/gimp.c
index 8d15eb8035..5530b8df2b 100644
--- a/libgimp/gimp.c
+++ b/libgimp/gimp.c
@@ -517,6 +517,12 @@ gimp_quit (void)
  * this case, the given @menu_label will only be used as the
  * procedure's user-visible name in the keyboard shortcut editor.
  *
+ * @image_types is a comma separated list of image types, or actually
+ * drawable types, that this procedure can deal with. Wildcards are
+ * possible here, so you could say "RGB*" instead of "RGB, RGBA" or
+ * "*" for all image types. If the procedure doesn't need an image to
+ * run, use the empty string.
+ *
  * @type must be one of #GIMP_PLUGIN or #GIMP_EXTENSION. Note that
  * temporary procedures must be installed using
  * gimp_install_temp_proc().