diff --git a/ChangeLog b/ChangeLog
index edb52682..1374ffad 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -14,6 +14,8 @@
 - clip coding and interpretation on vips image read
 - check image bounds for GIF load
 - prevent over-pre-shrink in thumbnail [kleisauke]
+- fix sharpen with sigma 0.5 [2h4dl]
+- sharpen restores input colourspace
 
 24/5/19 started 8.8.1
 - improve realpath() use on older libc
diff --git a/libvips/convolution/sharpen.c b/libvips/convolution/sharpen.c
index dc817575..38df2e48 100644
--- a/libvips/convolution/sharpen.c
+++ b/libvips/convolution/sharpen.c
@@ -39,6 +39,9 @@
  * 	- swap "radius" for "sigma", allows finer control
  * 	- allow a much greater range of parameters
  * 	- move to defaults suitable for screen output
+ * 28/8/19
+ * 	- fix sigma 0.5 case (thanks 2h4dl)
+ * 	- restore input colourspace
  */
 
 /*
@@ -170,11 +173,12 @@ vips_sharpen_build( VipsObject *object )
 {
 	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
 	VipsSharpen *sharpen = (VipsSharpen *) object;
-	VipsImage **t = (VipsImage **) vips_object_local_array( object, 7 );
+	VipsImage **t = (VipsImage **) vips_object_local_array( object, 8 );
 	VipsImage **args = (VipsImage **) vips_object_local_array( object, 2 );
 
 	VipsImage *in;
 	int i;
+	VipsInterpretation old_interpretation;
 
 	VIPS_GATE_START( "vips_sharpen_build: build" ); 
 
@@ -190,6 +194,7 @@ vips_sharpen_build( VipsObject *object )
 
 	in = sharpen->in; 
 
+	old_interpretation = in->Type;
 	if( vips_colourspace( in, &t[0], VIPS_INTERPRETATION_LABS, NULL ) )
 		return( -1 );
 	in = t[0];
@@ -199,10 +204,10 @@ vips_sharpen_build( VipsObject *object )
 		vips_check_format( class->nickname, in, VIPS_FORMAT_SHORT ) )
   		return( -1 );
 
-	/* Stop at 20% of max ... a bit mean. We always sharpen a short, 
+	/* Stop at 10% of max ... a bit mean. We always sharpen a short, 
 	 * so there's no point using a float mask. 
 	 */
-	if( vips_gaussmat( &t[1], sharpen->sigma, 0.2, 
+	if( vips_gaussmat( &t[1], sharpen->sigma, 0.1, 
 		"separable", TRUE,
 		"precision", VIPS_PRECISION_INTEGER,
 		NULL ) )
@@ -284,10 +289,11 @@ vips_sharpen_build( VipsObject *object )
 
 	g_object_set( object, "out", vips_image_new(), NULL ); 
 
-	/* Reattach the rest.
+	/* Reattach the rest, back to the start colourspace.
 	 */
 	if( vips_bandjoin2( t[5], t[3], &t[6], NULL ) ||
-		vips_image_write( t[6], sharpen->out ) )
+		vips_colourspace( t[6], &t[7], old_interpretation, NULL ) ||
+		vips_image_write( t[7], sharpen->out ) )
 		return( -1 );
 
 	VIPS_GATE_STOP( "vips_sharpen_build: build" );