diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 964cb156b..36a2ff228 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -207,6 +207,8 @@ a.k.a. the Latest source entry point in the app (invoked by tapping on the "Late
 #### Chapter
 
 - After a chapter list for the manga is fetched and the app is going to cache the data, `prepareNewChapter` will be called.
+- `SChapter.date_upload` is in the [UNIX Epoch time](https://en.wikipedia.org/wiki/Unix_time) format.
+    - If you don't pass `SChapter.date_upload`, the user won't get notifications for new chapters. refer to [this issue](https://github.com/inorichi/tachiyomi/issues/2089) for more info.
 
 #### Chapter Pages