diff --git a/ChangeLog b/ChangeLog
index 8df93af0..6bdc6f3a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,8 @@
 19/10/13 started 7.37.0
 - redone im_rotate_*mask45(), im_gauss_*mask*(), im_log_*mask(), im_dilate(),
   im_erode(), im_rank_image(), im_compass(), im_linedet(), im_gradient(),
-  im_convsep(), im_convsep_f(), im_fastcor(), im_spcor() as classes
+  im_convsep(), im_convsep_f(), im_fastcor(), im_spcor(), im_sharpen()
+  as classes
 - im_gradcor() deprecated
 - vips_init() now does some ABI compat checking, though this change requires
   an ABI break
diff --git a/TODO b/TODO
index c749f1fb..7c1bd978 100644
--- a/TODO
+++ b/TODO
@@ -1,10 +1,10 @@
-- try:
 
-	$ vips colourspace Opera-icon-high-res.png x.v labs
-	$ header x.v
-	x.v: 3056x3325 float, 4 bands, labs, pngload
+- add vips_gaussian_blur() with approx / int / float precision, maybe
+  vips_resize() as well?
 
-  o.O should be short innit?
+  could share a base class with vips_sharpen()/
+
+- do morph quickly as simple wrappers over the vips7 operations
 
 - support --strip for other writers
 
@@ -20,11 +20,6 @@
 
   note on memuse page
 
-- do conv and morph quickly as simple wrappers over the vips7 operations
-
-- add vips_gaussian_blur() with approx / int / float precision, maybe
-  vips_resize() as well?
-
 - do much fancier profiling with timing on all locks saved in memory and
   dumped on exit
 
diff --git a/libvips/colour/colour.c b/libvips/colour/colour.c
index 2d024425..3f12c499 100644
--- a/libvips/colour/colour.c
+++ b/libvips/colour/colour.c
@@ -481,12 +481,11 @@ vips_colour_code_build( VipsObject *object )
 	VipsColour *colour = VIPS_COLOUR( object );
 	VipsColourCode *code = VIPS_COLOUR_CODE( object );
 	VipsColourCodeClass *class = VIPS_COLOUR_CODE_GET_CLASS( object ); 
+	VipsImage **t = (VipsImage **) vips_object_local_array( object, 6 );
 
-	VipsImage **t;
 	VipsImage *in;
 	VipsImage *extra;
 
-	t = (VipsImage **) vips_object_local_array( object, 5 );
 
 	in = code->in;
 	extra = NULL;
@@ -559,15 +558,19 @@ vips_colour_code_build( VipsObject *object )
 		return( -1 );
 
 	/* Reattach higher bands, if necessary.
+	 *
+	 * Our processing on the first three bands may have changed the image
+	 * format. For example, converting LAB to LABS will make a short
+	 * image. We need to force the extra bands to match this new type. 
 	 */
 	if( extra ) {
 		VipsImage *x;
 
-		if( vips_bandjoin2( colour->out, extra, &x, NULL ) )
+		if( vips_cast( extra, &t[5], colour->out->BandFmt, NULL ) ||
+			vips_bandjoin2( colour->out, t[5], &x, NULL ) )
 			return( -1 );
 
 		VIPS_UNREF( colour->out );
-
 		colour->out = x;
 	}