diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index cbe02a37..9442d75e 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -43,6 +43,14 @@ responsibility for the copyright status of the code.
 
 We won't reject patches that lack S-o-b, but it is strongly recommended.
 
+When you re-send patches, revised or not, it would be very good to document the
+changes compared to the previous revision in the commit message and/or the
+cover letter. If you have already received Reviewed-by or Acked-by tags, you
+should evaluate whether they still apply and include them in the respective
+commit messages. Otherwise the tags may be lost, reviewers miss the credit they
+deserve, and the patches may cause redundant review effort.
+
+
 Tracking patches and following up
 ---------------------------------