diff --git a/libvips/iofuncs/generate.c b/libvips/iofuncs/generate.c
index a2cbf6f6..24f55717 100644
--- a/libvips/iofuncs/generate.c
+++ b/libvips/iofuncs/generate.c
@@ -182,7 +182,6 @@ vips__link_break_all( VipsImage *image )
 		(VipsSListMap2Fn) vips__link_break, image, NULL );
 	vips_slist_map2( image->downstream, 
 		(VipsSListMap2Fn) vips__link_break_rev, image, NULL );
-	g_mutex_unlock( vips__global_lock );
 
 	g_mutex_unlock( vips__global_lock );
 
diff --git a/libvips/iofuncs/image.c b/libvips/iofuncs/image.c
index 20ec4395..f2920cca 100644
--- a/libvips/iofuncs/image.c
+++ b/libvips/iofuncs/image.c
@@ -2201,7 +2201,8 @@ vips__image_wio_output( VipsImage *image )
  * @image: image to make read-write
  *
  * Gets @image ready for an in-place operation, such as im_insertplace().
- * Operations like this both read and write with VIPS_IMAGE_ADDR().
+ * After calling this function you can both read and write the image with 
+ * VIPS_IMAGE_ADDR().
  *
  * See also: im_insertplace(), vips_image_wio_input().
  *