diff --git a/TODO b/TODO
index 0b95dc15..54c52f7c 100644
--- a/TODO
+++ b/TODO
@@ -1,3 +1,14 @@
+- set res_unit meta in im_tiff2vips, then use that to set res unit default in
+  im_vips2tiff
+
+- setting :res_inch as a tiff option does not multiply by 2.54 :-( ie.
+
+	  1 pixel per mm vips image
+	  save as a tiff with res_cm
+	  sets 10 pixels / cm
+	  save as a tiff with res_inch
+	  sets 10 pixels / inch ... wrong!
+
 - should check for gettext in configure? see
 
 https://sourceforge.net/tracker/index.php?func=detail&aid=1836080&group_id=100050&atid=626186