diff --git a/src/binary_formats.ml b/src/binary_formats.ml
index 9dd88d65..2eb61c6b 100644
--- a/src/binary_formats.ml
+++ b/src/binary_formats.ml
@@ -13,7 +13,10 @@
    (from https://docs.taler.net/taler-developer-manual.html) *)
 
 (* TODO
-   - check that our struct are well "packed"
+   - check that our struct are well packed
+     - it looks like Bin only define packed structs
+     - we don't need to worry about struct having "P" suffix
+       remove them
    - test them
    - some purpose (`TALER_SIGNATURE_XXX`) are missing
      exchange and gana master branch are not in sync