diff --git a/ChangeLog b/ChangeLog
index 5c0f46ec..076b639c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -64,6 +64,7 @@
 - added im_gauss_dmask_sep()
 - laplacian generator lost -ve lobes for large sigma
 - added im_aconv(), approximate convolution
+- bumped smalltile to 512x512 for testing
 
 30/11/10 started 7.24.0
 - bump for new stable
diff --git a/libvips/convolution/im_aconv.c b/libvips/convolution/im_aconv.c
index ed47efe6..2a011c2a 100644
--- a/libvips/convolution/im_aconv.c
+++ b/libvips/convolution/im_aconv.c
@@ -40,9 +40,9 @@
  */
 
 /*
- */
 #define DEBUG
 #define VIPS_DEBUG
+ */
 
 #ifdef HAVE_CONFIG_H
 #include <config.h>
@@ -275,7 +275,6 @@ lines_new( IMAGE *in, IMAGE *out, DOUBLEMASK *mask, int n_layers )
 	lines->rounding = (lines->area + 1) / 2;
 
 	/* ASCII-art layer drawing.
-	 */
 	printf( "lines:\n" );
 	for( z = 0; z < lines->n_lines; z++ ) {
 		printf( "%3d - %2d x ", z, lines->factor[z] );
@@ -291,6 +290,7 @@ lines_new( IMAGE *in, IMAGE *out, DOUBLEMASK *mask, int n_layers )
 	}
 	printf( "area = %d\n", lines->area );
 	printf( "rounding = %d\n", lines->rounding );
+	 */
 
 	return( lines );
 }
diff --git a/libvips/include/vips/private.h b/libvips/include/vips/private.h
index ed718629..cfbe348e 100644
--- a/libvips/include/vips/private.h
+++ b/libvips/include/vips/private.h
@@ -136,8 +136,8 @@ typedef enum region_type {
  * vips_image_generate()
  * when acting as a data sink.
  */
-#define VIPS__TILE_WIDTH (64)
-#define VIPS__TILE_HEIGHT (64)
+#define VIPS__TILE_WIDTH (512)
+#define VIPS__TILE_HEIGHT (512)
 
 /* The height of the strips for the other two request styles.
  */
diff --git a/tools/vips.c b/tools/vips.c
index d9ace2bc..064c46e2 100644
--- a/tools/vips.c
+++ b/tools/vips.c
@@ -1062,6 +1062,7 @@ main( int argc, char **argv )
 	/* Could be a vips7 im_function.
 	 */
 	if( action && !handled && (fn = im_find_function( action )) ) {
+		(void) add_main_group( context, NULL );
 		parse_options( context, &argc, argv );
 
 		if( im_run_command( action, argc - 1, argv + 1 ) ) {