diff --git a/ChangeLog b/ChangeLog
index 36b7ef1d..37a38bd1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,6 +1,7 @@
 7/10/15 started 8.2.0
 - added im_bufmagick2vips(), a vips7 wrapper for magick load from buffer
 - fetch unset property now returns default value rather than warning
+- many more const declarations to help gobject-introspection
 
 7/5/15 started 8.1.1
 - oop, vips-8.0 should be vips-8.1, thanks Danilo
diff --git a/libvips/foreign/foreign.c b/libvips/foreign/foreign.c
index 37f77d52..2c90622a 100644
--- a/libvips/foreign/foreign.c
+++ b/libvips/foreign/foreign.c
@@ -553,7 +553,7 @@ vips_foreign_load( const char *name, VipsImage **out, ... )
  */
 static void *
 vips_foreign_find_load_buffer_sub( VipsForeignLoadClass *load_class, 
-	void **buf, size_t *len )
+	const void **buf, size_t *len )
 {
 	if( load_class->is_a_buffer &&
 		load_class->is_a_buffer( *buf, *len ) ) 
@@ -576,7 +576,7 @@ vips_foreign_find_load_buffer_sub( VipsForeignLoadClass *load_class,
  * error.
  */
 const char *
-vips_foreign_find_load_buffer( void *data, size_t size )
+vips_foreign_find_load_buffer( const void *data, size_t size )
 {
 	VipsForeignLoadClass *load_class;
 
@@ -630,7 +630,7 @@ vips_foreign_is_a( const char *loader, const char *filename )
  * Returns: %TRUE if @data can be loaded by @loader.
  */
 gboolean
-vips_foreign_is_a_buffer( const char *loader, void *data, size_t size )
+vips_foreign_is_a_buffer( const char *loader, const void *data, size_t size )
 {
 	VipsObjectClass *class;
 	VipsForeignLoadClass *load_class;
diff --git a/libvips/foreign/jpeg2vips.c b/libvips/foreign/jpeg2vips.c
index c61ceabd..b776f3a3 100644
--- a/libvips/foreign/jpeg2vips.c
+++ b/libvips/foreign/jpeg2vips.c
@@ -1157,7 +1157,7 @@ typedef struct {
 	/* Private stuff during read.
 	 */
 	gboolean start_of_file;	/* have we gotten any data yet? */
-	JOCTET *buf;
+	const JOCTET *buf;
 	size_t len;
 } InputBuffer;
 
@@ -1288,7 +1288,7 @@ term_source (j_decompress_ptr cinfo)
  */
 
 static void
-readjpeg_buffer (ReadJpeg *jpeg, void *buf, size_t len)
+readjpeg_buffer (ReadJpeg *jpeg, const void *buf, size_t len)
 {
   j_decompress_ptr cinfo = &jpeg->cinfo;
   InputBuffer *src;
@@ -1320,7 +1320,7 @@ readjpeg_buffer (ReadJpeg *jpeg, void *buf, size_t len)
 }
 
 int
-vips__jpeg_read_buffer( void *buf, size_t len, VipsImage *out, 
+vips__jpeg_read_buffer( const void *buf, size_t len, VipsImage *out, 
 	gboolean header_only, int shrink, int fail, gboolean readbehind, 
 	gboolean autorotate )
 {
@@ -1344,9 +1344,9 @@ vips__jpeg_read_buffer( void *buf, size_t len, VipsImage *out,
 }
 
 int
-vips__isjpeg_buffer( void *buf, size_t len )
+vips__isjpeg_buffer( const void *buf, size_t len )
 {
-	guchar *str = (guchar *) buf;
+	const guchar *str = (const guchar *) buf;
 
 	if( len >= 2 &&
 		str[0] == 0xff && 
diff --git a/libvips/foreign/jpegload.c b/libvips/foreign/jpegload.c
index cc8cee83..3a5fa031 100644
--- a/libvips/foreign/jpegload.c
+++ b/libvips/foreign/jpegload.c
@@ -302,7 +302,7 @@ vips_foreign_load_jpeg_buffer_load( VipsForeignLoad *load )
 }
 
 static gboolean
-vips_foreign_load_jpeg_buffer_is_a( void *buf, size_t len )
+vips_foreign_load_jpeg_buffer_is_a( const void *buf, size_t len )
 {
 	return( vips__isjpeg_buffer( buf, len ) );
 }
diff --git a/libvips/foreign/magickload.c b/libvips/foreign/magickload.c
index d2ec6ddb..b73efa0a 100644
--- a/libvips/foreign/magickload.c
+++ b/libvips/foreign/magickload.c
@@ -219,7 +219,7 @@ G_DEFINE_TYPE( VipsForeignLoadMagickBuffer, vips_foreign_load_magick_buffer,
 	vips_foreign_load_magick_get_type() );
 
 static gboolean
-vips_foreign_load_magick_buffer_is_a_buffer ( void* buf, size_t len )
+vips_foreign_load_magick_buffer_is_a_buffer( const void *buf, size_t len )
 {
 	VipsImage *t;
 	int result;
diff --git a/libvips/foreign/tiff.h b/libvips/foreign/tiff.h
index 50644094..06ae580e 100644
--- a/libvips/foreign/tiff.h
+++ b/libvips/foreign/tiff.h
@@ -55,12 +55,12 @@ int vips__tiff_read_header( const char *filename, VipsImage *out, int page );
 int vips__tiff_read( const char *filename, VipsImage *out, 
 	int page, gboolean readbehind );
 gboolean vips__istifftiled( const char *filename );
-gboolean vips__istiff_buffer( void *buf, size_t len );
+gboolean vips__istiff_buffer( const void *buf, size_t len );
 gboolean vips__istiff( const char *filename );
 
-int vips__tiff_read_header_buffer( void *buf, size_t len, VipsImage *out, 
+int vips__tiff_read_header_buffer( const void *buf, size_t len, VipsImage *out, 
 	int page );
-int vips__tiff_read_buffer( void *buf, size_t len, VipsImage *out, 
+int vips__tiff_read_buffer( const void *buf, size_t len, VipsImage *out, 
 	int page, gboolean readbehind );
 
 #ifdef __cplusplus
diff --git a/libvips/foreign/tiff2vips.c b/libvips/foreign/tiff2vips.c
index b1a24127..fb620d87 100644
--- a/libvips/foreign/tiff2vips.c
+++ b/libvips/foreign/tiff2vips.c
@@ -224,7 +224,7 @@ typedef struct _ReadTiff {
 	/* Parameters.
 	 */
 	char *filename;
-	void *buf;
+	const void *buf;
 	size_t len;
 	VipsImage *out;
 	int page;
@@ -1870,7 +1870,7 @@ my_tiff_unmap( thandle_t st, tdata_t start, toff_t len )
 }
 
 static ReadTiff *
-readtiff_new_buffer( void *buf, size_t len, VipsImage *out, int page, 
+readtiff_new_buffer( const void *buf, size_t len, VipsImage *out, int page, 
 	gboolean readbehind )
 {
 	ReadTiff *rtiff;
@@ -1991,7 +1991,7 @@ vips__istifftiled( const char *filename )
 }
 
 gboolean
-vips__istiff_buffer( void *buf, size_t len )
+vips__istiff_buffer( const void *buf, size_t len )
 {
 	char *str = (char *) buf; 
 
@@ -2018,7 +2018,8 @@ vips__istiff( const char *filename )
 }
 
 int
-vips__tiff_read_header_buffer( void *buf, size_t len, VipsImage *out, int page )
+vips__tiff_read_header_buffer( const void *buf, size_t len, 
+	VipsImage *out, int page )
 {
 	ReadTiff *rtiff;
 
@@ -2034,8 +2035,8 @@ vips__tiff_read_header_buffer( void *buf, size_t len, VipsImage *out, int page )
 }
 
 int
-vips__tiff_read_buffer( void *buf, size_t len, VipsImage *out, 
-	int page, gboolean readbehind )
+vips__tiff_read_buffer( const void *buf, size_t len, 
+	VipsImage *out, int page, gboolean readbehind )
 {
 	ReadTiff *rtiff;
 
diff --git a/libvips/foreign/vipsjpeg.h b/libvips/foreign/vipsjpeg.h
index 305ff5b2..9c86cb5c 100644
--- a/libvips/foreign/vipsjpeg.h
+++ b/libvips/foreign/vipsjpeg.h
@@ -48,12 +48,12 @@ int vips__jpeg_write_buffer( VipsImage *in,
 	gboolean no_subsample, gboolean trellis_quant,
 	gboolean overshoot_deringing, gboolean optimize_scans );
 
-int vips__isjpeg_buffer( void *buf, size_t len );
+int vips__isjpeg_buffer( const void *buf, size_t len );
 int vips__isjpeg( const char *filename );
 int vips__jpeg_read_file( const char *name, VipsImage *out, 
 	gboolean header_only, int shrink, gboolean fail, gboolean readbehind,
 	gboolean autorotate );
-int vips__jpeg_read_buffer( void *buf, size_t len, VipsImage *out, 
+int vips__jpeg_read_buffer( const void *buf, size_t len, VipsImage *out, 
 	gboolean header_only, int shrink, int fail, gboolean readbehind,
 	gboolean autorotate );
 
diff --git a/libvips/foreign/vipspng.c b/libvips/foreign/vipspng.c
index 30ea4ab0..155d2032 100644
--- a/libvips/foreign/vipspng.c
+++ b/libvips/foreign/vipspng.c
@@ -147,7 +147,7 @@ typedef struct {
 
 	/* For memory input.
 	 */
-	char *buffer;
+	const void *buffer;
 	size_t length;
 	size_t read_pos;
 
@@ -614,8 +614,8 @@ vips__png_read( const char *filename, VipsImage *out, gboolean readbehind )
 	return( 0 );
 }
 
-int
-vips__png_ispng_buffer( void *buf, size_t len )
+gboolean
+vips__png_ispng_buffer( const void *buf, size_t len )
 {
 	if( len >= 8 &&
 		!png_sig_cmp( (png_bytep) buf, 0, 8 ) )
@@ -650,7 +650,7 @@ vips_png_read_buffer( png_structp pPng, png_bytep data, png_size_t length )
 }
 
 static Read *
-read_new_buffer( VipsImage *out, char *buffer, size_t length, 
+read_new_buffer( VipsImage *out, const void *buffer, size_t length, 
 	gboolean readbehind )
 {
 	Read *read;
@@ -677,7 +677,7 @@ read_new_buffer( VipsImage *out, char *buffer, size_t length,
 }
 
 int
-vips__png_header_buffer( char *buffer, size_t length, VipsImage *out )
+vips__png_header_buffer( const void *buffer, size_t length, VipsImage *out )
 {
 	Read *read;
 
@@ -689,7 +689,7 @@ vips__png_header_buffer( char *buffer, size_t length, VipsImage *out )
 }
 
 int
-vips__png_read_buffer( char *buffer, size_t length, VipsImage *out, 
+vips__png_read_buffer( const void *buffer, size_t length, VipsImage *out, 
 	gboolean readbehind  )
 {
 	Read *read;
diff --git a/libvips/foreign/vipspng.h b/libvips/foreign/vipspng.h
index 843999b6..053aad6b 100644
--- a/libvips/foreign/vipspng.h
+++ b/libvips/foreign/vipspng.h
@@ -37,13 +37,14 @@ extern "C" {
 
 int vips__png_header( const char *name, VipsImage *out );
 int vips__png_read( const char *name, VipsImage *out, gboolean readbehind );
-int vips__png_ispng_buffer( void *buf, size_t len );
+gboolean vips__png_ispng_buffer( const void *buf, size_t len );
 int vips__png_ispng( const char *filename );
 gboolean vips__png_isinterlaced( const char *filename );
 extern const char *vips__png_suffs[];
-int vips__png_read_buffer( char *buffer, size_t length, VipsImage *out, 
-	gboolean readbehind  );
-int vips__png_header_buffer( char *buffer, size_t length, VipsImage *out );
+int vips__png_read_buffer( const void *buffer, size_t length, 
+	VipsImage *out, gboolean readbehind  );
+int vips__png_header_buffer( const void *buffer, size_t length, 
+	VipsImage *out );
 
 int vips__png_write( VipsImage *in, const char *filename, 
 	int compress, int interlace, const char *profile,
diff --git a/libvips/foreign/webp.h b/libvips/foreign/webp.h
index 28bf0906..1f750ec5 100644
--- a/libvips/foreign/webp.h
+++ b/libvips/foreign/webp.h
@@ -37,14 +37,16 @@ extern "C" {
 
 extern const char *vips__webp_suffs[];
 
-int vips__iswebp_buffer( void *buf, size_t len );
+int vips__iswebp_buffer( const void *buf, size_t len );
 int vips__iswebp( const char *filename );
 
 int vips__webp_read_file_header( const char *name, VipsImage *out ); 
 int vips__webp_read_file( const char *name, VipsImage *out ); 
 
-int vips__webp_read_buffer_header( void *buf, size_t len, VipsImage *out ); 
-int vips__webp_read_buffer( void *buf, size_t len, VipsImage *out ); 
+int vips__webp_read_buffer_header( const void *buf, size_t len, 
+	VipsImage *out ); 
+int vips__webp_read_buffer( const void *buf, size_t len, 
+	VipsImage *out ); 
 
 int vips__webp_write_file( VipsImage *out, const char *filename, 
 	int Q, gboolean lossless );
diff --git a/libvips/foreign/webp2vips.c b/libvips/foreign/webp2vips.c
index 7c41808e..722195b8 100644
--- a/libvips/foreign/webp2vips.c
+++ b/libvips/foreign/webp2vips.c
@@ -69,10 +69,10 @@ typedef struct {
 	 */
 	char *filename;
 
-	/* Memory source. We se gint64 rather than size_t since we use
+	/* Memory source. We use gint64 rather than size_t since we use
 	 * vips_file_length() and vips__mmap() for file sources.
 	 */
-	void *data;
+	const void *data;
 	gint64 length;
 
 	/* If we are opening a file object, the fd.
@@ -89,7 +89,7 @@ typedef struct {
 } Read;
 
 int
-vips__iswebp_buffer( void *buf, size_t len )
+vips__iswebp_buffer( const void *buf, size_t len )
 {
 	if( len >= MINIMAL_HEADER &&
 		WebPGetInfo( buf, MINIMAL_HEADER, NULL, NULL ) )
@@ -132,7 +132,7 @@ read_free( Read *read )
 }
 
 static Read *
-read_new( const char *filename, void *data, size_t length )
+read_new( const char *filename, const void *data, size_t length )
 {
 	Read *read;
 
@@ -266,7 +266,7 @@ vips__webp_read_file( const char *filename, VipsImage *out )
 }
 
 int
-vips__webp_read_buffer_header( void *buf, size_t len, VipsImage *out ) 
+vips__webp_read_buffer_header( const void *buf, size_t len, VipsImage *out ) 
 {
 	Read *read;
 
@@ -285,7 +285,7 @@ vips__webp_read_buffer_header( void *buf, size_t len, VipsImage *out )
 }
 
 int
-vips__webp_read_buffer( void *buf, size_t len, VipsImage *out ) 
+vips__webp_read_buffer( const void *buf, size_t len, VipsImage *out ) 
 {
 	Read *read;
 
diff --git a/libvips/include/vips/foreign.h b/libvips/include/vips/foreign.h
index 554e213d..4ba61e5f 100644
--- a/libvips/include/vips/foreign.h
+++ b/libvips/include/vips/foreign.h
@@ -166,7 +166,7 @@ typedef struct _VipsForeignLoadClass {
 	 * This function should return %TRUE if the buffer contains an image of 
 	 * this type. 
 	 */
-	gboolean (*is_a_buffer)( void *data, size_t size );
+	gboolean (*is_a_buffer)( const void *data, size_t size );
 
 	/* Get the flags from a filename. 
 	 *
@@ -214,11 +214,12 @@ typedef struct _VipsForeignLoadClass {
 GType vips_foreign_load_get_type( void );
 
 const char *vips_foreign_find_load( const char *filename );
-const char *vips_foreign_find_load_buffer( void *data, size_t size );
+const char *vips_foreign_find_load_buffer( const void *data, size_t size );
 
 VipsForeignFlags vips_foreign_flags( const char *loader, const char *filename );
 gboolean vips_foreign_is_a( const char *loader, const char *filename );
-gboolean vips_foreign_is_a_buffer( const char *loader, void *data, size_t size );
+gboolean vips_foreign_is_a_buffer( const char *loader, 
+	const void *data, size_t size );
 
 #define VIPS_TYPE_FOREIGN_SAVE (vips_foreign_save_get_type())
 #define VIPS_FOREIGN_SAVE( obj ) \
diff --git a/libvips/include/vips/image.h b/libvips/include/vips/image.h
index e4d6b657..f47982cc 100644
--- a/libvips/include/vips/image.h
+++ b/libvips/include/vips/image.h
@@ -427,15 +427,17 @@ VipsImage *vips_image_new_from_file( const char *name, ... )
 VipsImage *vips_image_new_from_file_RW( const char *filename );
 VipsImage *vips_image_new_from_file_raw( const char *filename, 
 	int xsize, int ysize, int bands, guint64 offset );
-VipsImage *vips_image_new_from_memory( void *data, size_t size,
+VipsImage *vips_image_new_from_memory( const void *data, size_t size,
 	int width, int height, int bands, VipsBandFormat format );
-VipsImage *vips_image_new_from_buffer( void *buf, size_t len, 
+VipsImage *vips_image_new_from_buffer( const void *buf, size_t len, 
 	const char *option_string, ... )
 	__attribute__((sentinel));
 VipsImage *vips_image_new_matrix( int width, int height );
 VipsImage *vips_image_new_matrixv( int width, int height, ... );
 VipsImage *vips_image_new_matrix_from_array( int width, int height, 
-	double *array, int size );
+	const double *array, int size );
+VipsImage *vips_image_matrix_from_array( int width, int height, 
+	const double *array, int size );
 void vips_image_set_delete_on_close( VipsImage *image, 
 	gboolean delete_on_close );
 guint64 vips_get_disc_threshold( void );
diff --git a/libvips/include/vips/internal.h b/libvips/include/vips/internal.h
index c0bce202..bd36c0af 100644
--- a/libvips/include/vips/internal.h
+++ b/libvips/include/vips/internal.h
@@ -127,7 +127,7 @@ char *vips__b64_encode( const unsigned char *data, size_t data_length );
 unsigned char *vips__b64_decode( const char *buffer, size_t *data_length );
 
 void *vips__mmap( int fd, int writeable, size_t length, gint64 offset );
-int vips__munmap( void *start, size_t length );
+int vips__munmap( const void *start, size_t length );
 int vips_mapfile( VipsImage * );
 int vips_mapfilerw( VipsImage * );
 int vips_remapfilerw( VipsImage * );
diff --git a/libvips/iofuncs/image.c b/libvips/iofuncs/image.c
index 563e79aa..5969857b 100644
--- a/libvips/iofuncs/image.c
+++ b/libvips/iofuncs/image.c
@@ -1873,7 +1873,7 @@ vips_filename_get_options( const char *vips_filename )
  * See also: vips_foreign_find_load(), vips_foreign_is_a(), 
  * vips_image_write_to_file().
  *
- * Returns: the new #VipsImage, or %NULL on error.
+ * Returns: (transfer full): the new #VipsImage, or %NULL on error.
  */
 VipsImage *
 vips_image_new_from_file( const char *name, ... )
@@ -1910,7 +1910,7 @@ vips_image_new_from_file( const char *name, ... )
  *
  * See also: vips_draw_circle().
  *
- * Returns: the new #VipsImage, or %NULL on error.
+ * Returns: (transfer full): the new #VipsImage, or %NULL on error.
  */
 VipsImage *
 vips_image_new_from_file_RW( const char *filename )
@@ -1934,7 +1934,7 @@ vips_image_new_from_file_RW( const char *filename )
  *
  * See also: vips_copy(), vips_rawload(), vips_image_new_from_file().
  *
- * Returns: the new #VipsImage, or %NULL on error.
+ * Returns: (transfer full): the new #VipsImage, or %NULL on error.
  */
 VipsImage *
 vips_image_new_from_file_raw( const char *filename, 
@@ -1963,7 +1963,7 @@ vips_image_new_from_file_raw( const char *filename,
 
 /**
  * vips_image_new_from_memory:
- * @data: (array length=size) (element-type guint8) (transfer full): start of memory area
+ * @data: (array length=size) (element-type guint8) (transfer none): start of memory area
  * @size: length of memory area
  * @width: image width
  * @height: image height
@@ -1983,10 +1983,10 @@ vips_image_new_from_file_raw( const char *filename,
  *
  * See also: vips_image_new(), vips_image_write_to_memory().
  *
- * Returns: the new #VipsImage, or %NULL on error.
+ * Returns: (transfer full): the new #VipsImage, or %NULL on error.
  */
 VipsImage *
-vips_image_new_from_memory( void *data, size_t size,
+vips_image_new_from_memory( const void *data, size_t size,
 	int width, int height, int bands, VipsBandFormat format )
 {
 	VipsImage *image;
@@ -2026,7 +2026,7 @@ vips_image_new_from_memory( void *data, size_t size,
 
 /**
  * vips_image_new_from_buffer:
- * @buf: start of memory buffer
+ * @buf: (array length=len) (element-type guint8) (transfer none): image data
  * @len: length of memory buffer
  * @option_string: set of extra options as a string
  * @...: %NULL-terminated list of optional named arguments
@@ -2046,10 +2046,10 @@ vips_image_new_from_memory( void *data, size_t size,
  *
  * See also: vips_image_write_to_buffer().
  *
- * Returns: 0 on success, -1 on error
+ * Returns: (transfer full): the new #VipsImage, or %NULL on error.
  */
 VipsImage *
-vips_image_new_from_buffer( void *buf, size_t len, 
+vips_image_new_from_buffer( const void *buf, size_t len, 
 	const char *option_string, ... )
 {
 	const char *operation_name;
@@ -2094,7 +2094,7 @@ vips_image_new_from_buffer( void *buf, size_t len,
  *
  * See also: vips_image_new_matrixv()
  * 
- * Returns: the new #VipsImage, or %NULL on error.
+ * Returns: (transfer full): the new #VipsImage, or %NULL on error.
  */
 VipsImage *
 vips_image_new_matrix( int width, int height )
@@ -2138,7 +2138,7 @@ vips_image_new_matrix( int width, int height )
  *
  * See also: vips_image_new_matrix()
  * 
- * Returns: the new #VipsImage, or %NULL on error.
+ * Returns: (transfer full): the new #VipsImage, or %NULL on error.
  */
 VipsImage *
 vips_image_new_matrixv( int width, int height, ... )
@@ -2169,11 +2169,11 @@ vips_image_new_matrixv( int width, int height, ... )
  *
  * A binding-friendly version of vips_image_new_matrixv().
  *
- * Returns: the new #VipsImage, or %NULL on error.
+ * Returns: (transfer full): the new #VipsImage, or %NULL on error.
  */
 VipsImage *
 vips_image_new_matrix_from_array( int width, int height, 
-	double *array, int size )
+	const double *array, int size )
 {
 	VipsImage *matrix;
 	int x, y;
@@ -2198,6 +2198,26 @@ vips_image_new_matrix_from_array( int width, int height,
 	return( matrix ); 
 }
 
+/**
+ * vips_image_matrix_from_array:
+ * @width: image width
+ * @height: image height
+ * @array: (array length=size) (transfer none): array of elements
+ * @size: number of elements
+ *
+ * A renamed vips_image_new_matrix_from_array(). Some gobject bindings do not
+ * like more than one _new method.
+ *
+ * Returns: (transfer full): the new #VipsImage, or %NULL on error.
+ */
+VipsImage *
+vips_image_matrix_from_array( int width, int height, 
+	const double *array, int size )
+{
+	return( vips_image_new_matrix_from_array( width, height, 
+		array, size ) ); 
+}
+
 /**
  * vips_image_set_delete_on_close:
  * @image: image to set
diff --git a/libvips/iofuncs/mapfile.c b/libvips/iofuncs/mapfile.c
index 38a36554..3c7c3e3d 100644
--- a/libvips/iofuncs/mapfile.c
+++ b/libvips/iofuncs/mapfile.c
@@ -189,16 +189,16 @@ vips__mmap( int fd, int writeable, size_t length, gint64 offset )
 }
 
 int
-vips__munmap( void *start, size_t length )
+vips__munmap( const void *start, size_t length )
 {
 #ifdef OS_WIN32
-	if( !UnmapViewOfFile( start ) ) {
+	if( !UnmapViewOfFile( (void *) start ) ) {
 		vips_error_system( GetLastError(), "vips_mapfile",
 			"%s", _( "unable to UnmapViewOfFile" ) );
 		return( -1 );
 	}
 #else /*!OS_WIN32*/
-	if( munmap( start, length ) < 0 ) {
+	if( munmap( (void *) start, length ) < 0 ) {
 		vips_error_system( errno, "vips_mapfile", 
 			"%s", _( "unable to munmap file" ) );
 		return( -1 );