diff --git a/libvips/include/vips/object.h b/libvips/include/vips/object.h
index 4123a526..53e16397 100644
--- a/libvips/include/vips/object.h
+++ b/libvips/include/vips/object.h
@@ -296,11 +296,6 @@ typedef struct _VipsArgumentInstance {
  */
 typedef GHashTable VipsArgumentTable;
 
-VipsArgumentInstance *vips__argument_get_instance( 
-	VipsArgumentClass *argument_class,
-	VipsObject *object );
-VipsArgument *vips__argument_table_lookup( VipsArgumentTable *argument_class, 
-	GParamSpec *pspec );
 void vips__object_set_member( VipsObject *object, GParamSpec *pspec,
 	GObject **member, GObject *argument );
 typedef void *(*VipsArgumentMapFn)( VipsObject *object, GParamSpec *pspec,
@@ -622,7 +617,8 @@ GType vips_type_find( const char *basename, const char *nickname );
 const char *vips_nickname_find( GType type );
 
 void *vips_class_map_all( GType type, VipsClassMapFn fn, void *a );
-VipsObjectClass *vips_class_find( const char *basename, const char *nickname );
+const VipsObjectClass *vips_class_find( const char *basename, 
+	const char *nickname );
 
 VipsObject **vips_object_local_array( VipsObject *parent, int n );
 
diff --git a/libvips/iofuncs/object.c b/libvips/iofuncs/object.c
index 5e410bfa..77841dcc 100644
--- a/libvips/iofuncs/object.c
+++ b/libvips/iofuncs/object.c
@@ -2691,9 +2691,9 @@ test_name( VipsObjectClass *class, const char *nickname )
  *
  * See also: vips_type_find()
  *
- * Returns: the found class.
+ * Returns: (transfer none): the found class.
  */
-VipsObjectClass *
+const VipsObjectClass *
 vips_class_find( const char *basename, const char *nickname )
 {
 	const char *classname = basename ? basename : "VipsObject";
@@ -2802,7 +2802,7 @@ vips_type_find( const char *basename, const char *nickname )
 		g_type_is_a( hit->type, base ) ) 
 		type = hit->type;
 	else {
-		VipsObjectClass *class;
+		const VipsObjectClass *class;
 
 		if( !(class = vips_class_find( basename, nickname )) )
 			return( 0 );
diff --git a/libvips/iofuncs/rect.c b/libvips/iofuncs/rect.c
index 05eec762..a2f4ec15 100644
--- a/libvips/iofuncs/rect.c
+++ b/libvips/iofuncs/rect.c
@@ -203,12 +203,12 @@ vips_rect_unionrect( const VipsRect *r1, const VipsRect *r2, VipsRect *out )
 }
 
 /**
- * vips_rect_dup:
+ * vips_rect_dup: (skip)
  * @r: rectangle to duplicate
  *
  * Duplicate a rect to the heap. You need to free the result with vips_free().
  *
- * Returns: a pointer to copy of @r allocated on the heap.
+ * Returns: (transfer full): a pointer to copy of @r allocated on the heap.
  */
 VipsRect *
 vips_rect_dup( const VipsRect *r )