diff --git a/NewCapDesign.md b/NewCapDesign.md
index e92df5c..70e4244 100644
--- a/NewCapDesign.md
+++ b/NewCapDesign.md
@@ -117,4 +117,6 @@ established sense). To make them real, we need to:
    `tahoe://grid1234/D/MR/cryptobits` should reference
    `tahoe://grid1234/MR/cryptobits`. (#403)
  * #102 and #217 have notes on dircaps
+ * #678 (converge same file, same K, different M)
+