diff --git a/ChangeLog b/ChangeLog
index 81ee057f..3daefd12 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,7 @@
 - im_flood() and friends rewritten, typically 4x faster
 - removed --with-cimg option, added --disable-cxx
 - added im_system_image() (thanks Roland)
+- added postclose callbacks
 
 26/11/09 started 7.20.3
 - updated en_GB.po translation 
diff --git a/benchmark/benchmarkn.sh b/benchmark/benchmarkn.sh
index a702a730..a2cff47e 100755
--- a/benchmark/benchmarkn.sh
+++ b/benchmark/benchmarkn.sh
@@ -27,7 +27,7 @@ echo " by" `header -f Ysize temp.v` "pixels"
 echo "starting benchmark ..."
 echo "chain=$chain"
 
-for cpus in 1 2 ; do
+for cpus in 1 2 3 4 5 6 ; do
   export IM_CONCURRENCY=$cpus
 
   echo IM_CONCURRENCY=$IM_CONCURRENCY
diff --git a/libvips/conversion/conver_dispatch.c b/libvips/conversion/conver_dispatch.c
index fe234dcc..b04690af 100644
--- a/libvips/conversion/conver_dispatch.c
+++ b/libvips/conversion/conver_dispatch.c
@@ -92,26 +92,30 @@ static int
 system_image_vec( im_object *argv )
 {
 	IMAGE *in = argv[0];
-	char *in_format = argv[1];
-	char *out_format = argv[2];
-	char *cmd = argv[3];
-	char **log = (char **) &argv[4];
-	char **out_file = (char **) &argv[5];
+	IMAGE *out = argv[1];
+	char *in_format = argv[2];
+	char *out_format = argv[3];
+	char *cmd = argv[4];
+	char **log = (char **) &argv[5];
 
-	*out_file = im_system_image( in, in_format, out_format, cmd, log );
-	if( !*out_file )
-		*out_file = im_strdup( NULL, "" );
+	IMAGE *out_image;
 
+	if( (out_image = im_system_image( in, 
+		in_format, out_format, cmd, log )) )
+		im_copy_file( out_image, out );
+
+	/* We always succeed, but out may be invalid.
+	 */
 	return( 0 );
 }
 
 static im_arg_desc system_image_args[] = {
-	IM_INPUT_IMAGE( "im" ),
+	IM_INPUT_IMAGE( "in" ),
+	IM_OUTPUT_IMAGE( "out" ),
 	IM_INPUT_STRING( "in_format" ),
 	IM_INPUT_STRING( "out_format" ),
 	IM_INPUT_STRING( "command" ),
-	IM_OUTPUT_STRING( "log" ),
-	IM_OUTPUT_STRING( "out_file" )
+	IM_OUTPUT_STRING( "log" )
 };
 
 static im_function system_image_desc = {
diff --git a/libvips/conversion/im_copy_file.c b/libvips/conversion/im_copy_file.c
index 0a3763ce..0cf99434 100644
--- a/libvips/conversion/im_copy_file.c
+++ b/libvips/conversion/im_copy_file.c
@@ -60,7 +60,7 @@ im_copy_file( IMAGE *in, IMAGE *out )
 	if( !im_isfile( in ) ) {
 		IMAGE *disc;
 
-		if( !(disc = im__open_temp()) )
+		if( !(disc = im__open_temp( "%s.v" )) )
 			return( -1 );
 		if( im_add_close_callback( out, 
 			(im_callback_fn) im_close, disc, NULL ) ) {
diff --git a/libvips/conversion/im_system.c b/libvips/conversion/im_system.c
index a9edd45b..bca31d04 100644
--- a/libvips/conversion/im_system.c
+++ b/libvips/conversion/im_system.c
@@ -79,7 +79,7 @@ im_system( IMAGE *im, const char *cmd, char **out )
 	if( !im_isfile( im ) ) {
 		IMAGE *disc;
 
-		if( !(disc = im__open_temp()) )
+		if( !(disc = im__open_temp( "%s.v" )) )
 			return( -1 );
 		if( im_copy( im, disc ) ||
 			im_system( disc, cmd, out ) ) {
diff --git a/libvips/conversion/im_system_image.c b/libvips/conversion/im_system_image.c
index 45a48743..a40e8c8d 100644
--- a/libvips/conversion/im_system_image.c
+++ b/libvips/conversion/im_system_image.c
@@ -60,31 +60,20 @@
 
 static int
 system_image( IMAGE *im, 
-	const char *in_name, const char *out_name, const char *cmd_format, 
+	IMAGE *in_image, IMAGE *out_image, const char *cmd_format, 
 	char **log ) 
 {
-	IMAGE *disc;
+	const char *in_name = in_image->filename;
+	const char *out_name = out_image->filename;
 	FILE *fp;
 	char line[IM_MAX_STRSIZE];
 	char txt[IM_MAX_STRSIZE];
 	VipsBuf buf = VIPS_BUF_STATIC( txt );
 	int result;
 
-	if( !(disc = im_open( in_name, "w" )) ) 
+	if( im_copy( im, in_image ) || 
+		!(fp = im_popenf( cmd_format, "r", in_name, out_name )) ) 
 		return( -1 );
-	if( im_copy( im, disc ) ) {
-		im_close( im );
-		g_unlink( in_name );
-
-		return( -1 );
-	}
-	im_close( im );
-
-	if( !(fp = im_popenf( cmd_format, "r", in_name, out_name )) ) {
-		g_unlink( in_name );
-
-		return( -1 );
-	}
 
 	while( fgets( line, IM_MAX_STRSIZE, fp ) ) 
 		if( !vips_buf_appends( &buf, line ) )
@@ -92,15 +81,14 @@ system_image( IMAGE *im,
 
 	result = pclose( fp );
 
-	g_unlink( in_name );
-
 	if( log )
 		*log = im_strdup( NULL, vips_buf_all( &buf ) );
 
 	return( result );
 }
 
-/* 
+/**
+ * im_system_image:
 
    Run a command on an image, returning a new image.
 
@@ -127,29 +115,29 @@ system_image( IMAGE *im,
  
   */
 
-char *
+IMAGE *
 im_system_image( IMAGE *im, 
 	const char *in_format, const char *out_format, const char *cmd_format, 
 	char **log )
 {
-	char *in_name;
-	char *out_name;
+	IMAGE *in_image;
+	IMAGE *out_image;
 
 	if( log )
 		*log = NULL;
 
-	in_name = im__temp_name( in_format );
-	out_name = im__temp_name( in_format );
+	in_image = im__open_temp( in_format );
+	out_image = im__open_temp( out_format );
 
-	if( !in_name || 
-		!out_name ||
-		system_image( im, in_name, out_name, cmd_format, log ) ) {
-		g_free( in_name );
-		g_free( out_name );
+	if( !in_image || 
+		!out_image ||
+		system_image( im, in_image, out_image, cmd_format, log ) ) {
+		im_close( in_image );
+		im_close( out_image );
 
 		return( NULL );
 	}
-	g_free( in_name );
+	im_close( in_image );
 
-	return( out_name );
+	return( out_image );
 }
diff --git a/libvips/include/vips/callback.h b/libvips/include/vips/callback.h
index 0f19fc0f..1fe5a98f 100644
--- a/libvips/include/vips/callback.h
+++ b/libvips/include/vips/callback.h
@@ -40,6 +40,7 @@ typedef int (*im_callback_fn)( void *a, void *b );
 
 int im_add_close_callback( IMAGE *im, im_callback_fn fn, void *a, void *b );
 int im_add_preclose_callback( IMAGE *im, im_callback_fn fn, void *a, void *b );
+int im_add_postclose_callback( IMAGE *im, im_callback_fn fn, void *a, void *b );
 
 int im_add_evalstart_callback( IMAGE *im, im_callback_fn fn, void *a, void *b );
 int im_add_eval_callback( IMAGE *im, im_callback_fn fn, void *a, void *b );
diff --git a/libvips/include/vips/conversion.h b/libvips/include/vips/conversion.h
index dd538ec8..11661fcb 100644
--- a/libvips/include/vips/conversion.h
+++ b/libvips/include/vips/conversion.h
@@ -111,7 +111,7 @@ int im_subsample( IMAGE *in, IMAGE *out, int x, int y );
 int im_zoom( IMAGE *in, IMAGE *out, int x, int y );
 
 int im_system( IMAGE *im, const char *cmd, char **out );
-char *im_system_image( IMAGE *im, 
+IMAGE *im_system_image( IMAGE *im, 
 	const char *in_format, const char *out_format, const char *cmd_format, 
 	char **log );
 
diff --git a/libvips/include/vips/image.h b/libvips/include/vips/image.h
index 39ad77cc..44bf7a23 100644
--- a/libvips/include/vips/image.h
+++ b/libvips/include/vips/image.h
@@ -240,6 +240,11 @@ typedef struct _VipsImage {
 	 * relationships, so it's a mandatory thing.
 	 */
 	gboolean hint_set;
+
+	/* Post-close callbacks happen on finalize. Eg. deleting the file
+	 * associated with this temp image.
+	 */
+	GSList *postclosefns; 	
 } VipsImage;
 
 extern const size_t im__sizeof_bandfmt[];
diff --git a/libvips/include/vips/util.h b/libvips/include/vips/util.h
index 949ec036..28c1411b 100644
--- a/libvips/include/vips/util.h
+++ b/libvips/include/vips/util.h
@@ -255,7 +255,7 @@ int im_isvips( const char *filename );
 int im_amiMSBfirst( void );
 
 char *im__temp_name( const char *format );
-IMAGE *im__open_temp( void );
+IMAGE *im__open_temp( const char *format );
 
 int im_bits_of_fmt( VipsBandFmt fmt );
 
diff --git a/libvips/iofuncs/callback.c b/libvips/iofuncs/callback.c
index 9ce363fa..f34894d4 100644
--- a/libvips/iofuncs/callback.c
+++ b/libvips/iofuncs/callback.c
@@ -108,11 +108,11 @@ add_callback( IMAGE *im, GSList **cblist, im_callback_fn fn, void *a, void *b )
  *
  * Attaches a close callback @fn to @im.
  *
- * Close callbacks are triggered exactly once when the image has been closed
+ * Close callbacks are triggered exactly once, when the image has been closed
  * and most resources freed, but just before the memory for @im is released.
  *
  * Close callbacks are a good place to free memory that was need to generate
- * @im, delete temporary files and so on. You can close other images and there
+ * @im. You can close other images and there
  * may even be circularity in your close lists.
  *
  * See also: im_malloc() (implemented with im_add_close_callback()),
@@ -127,6 +127,29 @@ im_add_close_callback( IMAGE *im, im_callback_fn fn, void *a, void *b )
 	return( add_callback( im, &im->closefns, fn, a, b ) );
 }
 
+/**
+ * im_add_postclose_callback:
+ * @im: image to attach callback to
+ * @fn: callback function
+ * @a: user data 1
+ * @b: user data 2
+ *
+ * Attaches a close callback @fn to @im.
+ *
+ * Post-close callbacks are triggered exactly once, just before the memory
+ * associated with @im is released. 
+ *
+ * Close callbacks are a good place to delete temporary files. You can close 
+ * other images and there may even be circularity in your close lists.
+ *
+ * Returns: 0 on success, or -1 on error.
+ */
+int
+im_add_postclose_callback( IMAGE *im, im_callback_fn fn, void *a, void *b )
+{	
+	return( add_callback( im, &im->postclosefns, fn, a, b ) );
+}
+
 /**
  * im_add_preclose_callback:
  * @im: image to attach callback to
diff --git a/libvips/iofuncs/debug.c b/libvips/iofuncs/debug.c
index 6bbae846..868b2ec3 100644
--- a/libvips/iofuncs/debug.c
+++ b/libvips/iofuncs/debug.c
@@ -393,16 +393,18 @@ im_printdesc( IMAGE *image )
 	 */
 	if( image->generate )
 		printf( "generate function attached\n" );
+	if( image->preclosefns )
+		printf( "preclose callbacks attached\n" );
 	if( image->closefns )
 		printf( "close callbacks attached\n" );
+	if( image->postclosefns )
+		printf( "postclose callbacks attached\n" );
 	if( image->evalfns )
 		printf( "eval callbacks attached\n" );
 	if( image->evalendfns )
 		printf( "evalend callbacks attached\n" );
 	if( image->evalstartfns )
 		printf( "evalstart callbacks attached\n" );
-	if( image->preclosefns )
-		printf( "preclose callbacks attached\n" );
 	if( image->invalidatefns )
 		printf( "invalidate callbacks attached\n" );
 	if( image->regions ) {
diff --git a/libvips/iofuncs/im_close.c b/libvips/iofuncs/im_close.c
index f1618d41..ecd099c0 100644
--- a/libvips/iofuncs/im_close.c
+++ b/libvips/iofuncs/im_close.c
@@ -50,6 +50,8 @@
  * 	  released
  * 6/10/09
  * 	- gtkdoc comment
+ * 10/1/09
+ * 	- added postclose
  */
 
 /*
@@ -294,6 +296,8 @@ im_close( IMAGE *im )
 
 		/* Final cleanup.
 		 */
+		result |= im__trigger_callbacks( im->postclosefns );
+		IM_FREEF( im_slist_free_all, im->postclosefns );
 		IM_FREEF( g_mutex_free, im->sslock );
 		IM_FREE( im->filename );
 		IM_FREE( im->Hist );
diff --git a/libvips/iofuncs/init.c b/libvips/iofuncs/init.c
index c0f727bb..0a496fb2 100644
--- a/libvips/iofuncs/init.c
+++ b/libvips/iofuncs/init.c
@@ -32,6 +32,8 @@
  *	- add file_length 
  * 8/10/09
  * 	- add set_hint
+ * 10/1/09
+ * 	- added postclose
  */
 
 /*
@@ -173,6 +175,8 @@ im_init( const char *filename )
 
 	im->hint_set = FALSE;
 
+	im->postclosefns = NULL;
+
 	if( !(im->filename = im_strdup( NULL, filename )) ) {
 		im_close( im );
 		return( NULL );
diff --git a/libvips/iofuncs/util.c b/libvips/iofuncs/util.c
index bbbd40a8..ea876d6c 100644
--- a/libvips/iofuncs/util.c
+++ b/libvips/iofuncs/util.c
@@ -1546,14 +1546,15 @@ im__temp_name( const char *format )
 }
 
 /* Make a disc IMAGE which will be automatically unlinked on im_close().
+ * Format is something like "%s.v" for a vips file.
  */
 IMAGE *
-im__open_temp( void )
+im__open_temp( const char *format )
 {
 	char *name;
 	IMAGE *disc;
 
-	if( !(name = im__temp_name( "%s.v" )) )
+	if( !(name = im__temp_name( format )) )
 		return( NULL );
 
 	if( !(disc = im_open( name, "w" )) ) {
@@ -1562,7 +1563,10 @@ im__open_temp( void )
 	}
 	g_free( name );
 
-	if( im_add_close_callback( disc, 
+	/* Needs to be postclose so we can rewindd disc after write without
+	 * deleting the file.
+	 */
+	if( im_add_postclose_callback( disc, 
 		(im_callback_fn) unlink, disc->filename, NULL ) ) {
 		im_close( disc );
 		g_unlink( name );
diff --git a/libvips/mask/rw_mask.c b/libvips/mask/rw_mask.c
index 75f02b3b..e22bd237 100644
--- a/libvips/mask/rw_mask.c
+++ b/libvips/mask/rw_mask.c
@@ -184,7 +184,7 @@ im_create_imask( const char *filename, int xs, int ys )
 
 INTMASK *
 im_create_imaskv( const char *filename, int xs, int ys, ... )
-{	
+{
 	va_list ap;
 
 	INTMASK *m;