diff --git a/src/binary_formats.ml b/src/binary_formats.ml
index a16aadb5..f6ec142a 100644
--- a/src/binary_formats.ml
+++ b/src/binary_formats.ml
@@ -41,7 +41,9 @@
 let int32_size = 4
 let int64_size = 8
 
-(* todo clean up: maybe rm it *)
+(* TODO clean up
+   ? rm all of UTIL_FUNC
+   ? Bin.map int64 to Ptime.t here *)
 module UTIL_FUNC = struct
   (* microseconds since the UNIX Epoch
    UINT64_MAX represents "never" *)