diff --git a/libvips/format/.radiance.c.swp b/libvips/format/.radiance.c.swp
new file mode 100644
index 00000000..6a558149
Binary files /dev/null and b/libvips/format/.radiance.c.swp differ
diff --git a/libvips/format/im_jpeg2vips.c b/libvips/format/im_jpeg2vips.c
index 2c4ec26d..6042cc2e 100644
--- a/libvips/format/im_jpeg2vips.c
+++ b/libvips/format/im_jpeg2vips.c
@@ -700,7 +700,7 @@ jpeg2vips( const char *name, IMAGE *out, gboolean header_only )
 
 	/* Make input.
 	 */
-        if( !(fp = im__file_open_read( filename, NULL )) ) 
+        if( !(fp = im__file_open_read( filename, NULL, FALSE )) ) 
                 return( -1 );
 	eman.fp = fp;
         jpeg_stdio_src( &cinfo, fp );
diff --git a/libvips/format/im_png2vips.c b/libvips/format/im_png2vips.c
index de311442..e459bc58 100644
--- a/libvips/format/im_png2vips.c
+++ b/libvips/format/im_png2vips.c
@@ -140,7 +140,7 @@ read_new( const char *name, IMAGE *out )
 	read->row_pointer = NULL;
 	read->data = NULL;
 
-        if( !(read->fp = im__file_open_read( name, NULL )) ) {
+        if( !(read->fp = im__file_open_read( name, NULL, FALSE )) ) {
 		read_destroy( read );
 		return( NULL );
 	}
diff --git a/libvips/format/im_ppm2vips.c b/libvips/format/im_ppm2vips.c
index ae61e985..aba1b102 100644
--- a/libvips/format/im_ppm2vips.c
+++ b/libvips/format/im_ppm2vips.c
@@ -419,7 +419,7 @@ ppm2vips_header( const char *filename, IMAGE *out )
 	int ascii;
 	int msb_first;
 
-	if( !(fp = im__file_open_read( filename, NULL )) ) 
+	if( !(fp = im__file_open_read( filename, NULL, FALSE )) ) 
                 return( -1 );
 	if( read_header( fp, out, &bits, &ascii, &msb_first ) ) {
 		fclose( fp );
@@ -442,7 +442,7 @@ isppmmmap( const char *filename )
 	int ascii;
 	int msb_first;
 
-	if( !(fp = im__file_open_read( filename, NULL )) ) 
+	if( !(fp = im__file_open_read( filename, NULL, FALSE )) ) 
                 return( -1 );
 
 	if( !(im = im_open( "temp", "p" )) ) {
@@ -481,7 +481,10 @@ im_ppm2vips( const char *filename, IMAGE *out )
 {
         FILE *fp;
 
-	if( !(fp = im__file_open_read( filename, NULL )) ) 
+	/* Note that we open in binary mode. If this is a binary PPM, we need
+	 * to be able to mmap it.
+	 */
+	if( !(fp = im__file_open_read( filename, NULL, FALSE )) ) 
                 return( -1 );
 	if( parse_ppm( fp, filename, out ) ) {
 		fclose( fp );
diff --git a/libvips/format/im_vips2jpeg.c b/libvips/format/im_vips2jpeg.c
index fbb7647b..6a55b97c 100644
--- a/libvips/format/im_vips2jpeg.c
+++ b/libvips/format/im_vips2jpeg.c
@@ -755,7 +755,7 @@ im_vips2jpeg( IMAGE *in, const char *filename )
 
 	/* Make output.
 	 */
-        if( !(write->eman.fp = im__file_open_write( name )) ) {
+        if( !(write->eman.fp = im__file_open_write( name, FALSE )) ) {
 		write_destroy( write );
                 return( -1 );
         }
diff --git a/libvips/format/im_vips2png.c b/libvips/format/im_vips2png.c
index b8076bad..9b0e78d5 100644
--- a/libvips/format/im_vips2png.c
+++ b/libvips/format/im_vips2png.c
@@ -370,7 +370,7 @@ im_vips2png( IMAGE *in, const char *filename )
 
 	/* Make output.
 	 */
-        if( !(write->fp = im__file_open_write( name )) ) {
+        if( !(write->fp = im__file_open_write( name, FALSE )) ) {
 		write_destroy( write );
 		return( -1 );
 	}
diff --git a/libvips/format/im_vips2ppm.c b/libvips/format/im_vips2ppm.c
index f869ab62..c89e53a9 100644
--- a/libvips/format/im_vips2ppm.c
+++ b/libvips/format/im_vips2ppm.c
@@ -87,7 +87,7 @@ write_new( IMAGE *in, const char *name )
 
 	write->in = in;
 	write->name = im_strdup( NULL, name );
-        write->fp = im__file_open_write( name );
+        write->fp = im__file_open_write( name, FALSE );
 
 	if( !write->name || !write->fp ) {
 		write_destroy( write );
diff --git a/libvips/format/radiance.c b/libvips/format/radiance.c
index d1a7d57c..4ea230e0 100644
--- a/libvips/format/radiance.c
+++ b/libvips/format/radiance.c
@@ -779,7 +779,7 @@ israd( const char *filename )
 	printf( "israd: \"%s\"\n", filename );
 #endif /*DEBUG*/
 
-        if( !(fin = im__file_open_read( filename, NULL )) ) 
+        if( !(fin = im__file_open_read( filename, NULL, FALSE )) ) 
 		return( 0 );
 	strcpy( format, PICFMT );
 	result = checkheader( fin, format, NULL );
@@ -825,7 +825,7 @@ read_new( const char *filename, IMAGE *out )
 	read->prims[3][1] = CIE_y_w;
 	read->buf = NULL;
 
-	if( !(read->fin = im__file_open_read( filename, NULL )) ) {
+	if( !(read->fin = im__file_open_read( filename, NULL, FALSE )) ) {
 		read_destroy( read );
 		return( NULL );
 	}
@@ -1052,7 +1052,7 @@ write_new( IMAGE *in, const char *filename )
 
 	write->in = in;
 	write->filename = im_strdup( NULL, filename );
-        write->fout = im__file_open_write( filename );
+        write->fout = im__file_open_write( filename, FALSE );
 	strcpy( write->format, COLRFMT );
 	write->expos = 1.0;
 	for( i = 0; i < 3; i++ )
diff --git a/libvips/mask/rw_mask.c b/libvips/mask/rw_mask.c
index a0cd43c0..e25c6459 100644
--- a/libvips/mask/rw_mask.c
+++ b/libvips/mask/rw_mask.c
@@ -482,7 +482,7 @@ im_read_dmask( const char *filename )
 	int x, y, i, size;
 	char buf[IM_MAX_LINE];
 
-	if( !(fp = im__file_open_read( filename, NULL )) ) 
+	if( !(fp = im__file_open_read( filename, NULL, TRUE )) ) 
 		return( NULL );
 
 	if( read_header( fp, &xs, &ys, &sc, &off ) ) {