diff --git a/ChangeLog b/ChangeLog
index 3cc6530a..06716c46 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -21,6 +21,7 @@
 - more VipsImage props
 - added vips_image_write(), old one becomes vips_image_write_to_file()
 - jpeg read/write copies over XMP data
+- handle offset correctly in separable convolutions (thanks Nicolas)
 
 12/9/11 started 7.26.4
 - fallback vips_init() 
diff --git a/TODO b/TODO
index 3f55b0c1..e006ab92 100644
--- a/TODO
+++ b/TODO
@@ -5,8 +5,6 @@
 
 
 
-- nicolas's convsep patch
-
 - add nifti support
 
 	http://niftilib.sourceforge.net/
diff --git a/libvips/convolution/im_conv.c b/libvips/convolution/im_conv.c
index e1671206..21151800 100644
--- a/libvips/convolution/im_conv.c
+++ b/libvips/convolution/im_conv.c
@@ -65,6 +65,8 @@
  * 	- add array tiling
  * 9/5/11
  * 	- argh typo in overflow estimation could cause errors
+ * 15/10/11 Nicolas
+ * 	- handle offset correctly in seperable convolutions
  */
 
 /*
@@ -1132,9 +1134,10 @@ im_convsep_raw( IMAGE *in, IMAGE *out, INTMASK *mask )
 
 	rmask->xsize = mask->ysize;
 	rmask->ysize = mask->xsize;
+        rmask->offset = 0.;
 
-	if( im_conv_raw( in, t, mask ) ||
-		im_conv_raw( t, out, rmask ) )
+	if( im_conv_raw( in, t, rmask ) ||
+		im_conv_raw( t, out, mask ) )
 		return( -1 );
 
 	return( 0 );
diff --git a/libvips/convolution/im_conv_f.c b/libvips/convolution/im_conv_f.c
index 3a29b3c2..9af1b048 100644
--- a/libvips/convolution/im_conv_f.c
+++ b/libvips/convolution/im_conv_f.c
@@ -41,6 +41,8 @@
  * 29/10/10
  * 	- get rid of im_convsep_f(), just call this twice, no longer worth
  * 	  keeping two versions
+ * 15/10/11 Nicolas
+ * 	- handle offset correctly in seperable convolutions
  */
 
 /*
@@ -410,9 +412,10 @@ im_convsep_f_raw( IMAGE *in, IMAGE *out, DOUBLEMASK *mask )
 
 	rmask->xsize = mask->ysize;
 	rmask->ysize = mask->xsize;
+        rmask->offset = 0.;
 
-	if( im_conv_f_raw( in, t, mask ) ||
-		im_conv_f_raw( t, out, rmask ) )
+	if( im_conv_f_raw( in, t, rmask ) ||
+		im_conv_f_raw( t, out, mask ) )
 		return( -1 );
 
 	return( 0 );