diff --git a/TODO b/TODO
index e9b70ff2..ad3d3c91 100644
--- a/TODO
+++ b/TODO
@@ -1,8 +1,20 @@
-- debug.c can go?
+- rewind is not removing arg instance flags
 
-  make sanity a method on object
+  VIPS-WARNING **: object.c:567: VipsImage can only assign 'nickname' once
 
-  tools/others/sines.c and friends can go
+       VipsArgumentInstance *argument_instance =
+               vips__argument_get_instance( argument_class, object );
+
+  how do we find and junk these? 
+
+	vips_object_dispose_argument(
+
+  runs, but perhaps does not trash instance storage? where is this released?
+
+
+
+
+- tools/others/sines.c and friends can go
 
 
 - why not rename VipsBandFormat as VipsFormat? cf. VipsCoding,
diff --git a/libvips/include/vips/object.h b/libvips/include/vips/object.h
index 949970ab..940de6ce 100644
--- a/libvips/include/vips/object.h
+++ b/libvips/include/vips/object.h
@@ -292,6 +292,8 @@ void vips_object_local_cb( VipsObject *vobject, GObject *gobject );
 void vips_object_print_all( void );
 void vips_object_sanity_all( void );
 
+void vips_object_rewind( VipsObject *object );
+
 #ifdef __cplusplus
 }
 #endif /*__cplusplus*/
diff --git a/libvips/iofuncs/check.c b/libvips/iofuncs/check.c
index 8027d2a8..5d8a912b 100644
--- a/libvips/iofuncs/check.c
+++ b/libvips/iofuncs/check.c
@@ -235,7 +235,7 @@ im_incheck( IMAGE *im )
 		/* Free any resources the image holds and reset to a base
 		 * state.
 		 */
-		g_object_run_dispose( G_OBJECT( im ) );
+		vips_object_rewind( VIPS_OBJECT( im ) );
 
 		/* And reopen .. recurse to get a mmaped image.
 		 */
@@ -456,7 +456,7 @@ im_pincheck( IMAGE *im )
 		/* Free any resources the image holds and reset to a base
 		 * state.
 		 */
-		g_object_run_dispose( G_OBJECT( im ) );
+		vips_object_rewind( VIPS_OBJECT( im ) );
 
 		g_object_set( im,
 			"mode", "r",
diff --git a/libvips/iofuncs/object.c b/libvips/iofuncs/object.c
index dc6dd8f3..dc765b5b 100644
--- a/libvips/iofuncs/object.c
+++ b/libvips/iofuncs/object.c
@@ -1244,3 +1244,18 @@ vips_object_sanity_all( void )
 {
 	vips_object_map( (VSListMap2Fn) vips_object_sanity_all_cb, NULL, NULL );
 }
+
+/* On a rewind, we dispose the old contents of the object and
+ * reconstruct. This is used in things like im_pincheck() where a "w"
+ * image has to be rewound and become a "p" image.
+ */
+void
+vips_object_rewind( VipsObject *object )
+{
+	g_object_run_dispose( G_OBJECT( object ) );
+
+	object->constructed = FALSE;
+	object->preclose = FALSE;
+	object->close = FALSE;
+	object->postclose = FALSE;
+}