diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index c8118f6a3..ce7b06835 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -244,3 +244,5 @@ Core developers should follow these rules when processing pull requests:
 * Always wait for tests to pass before merging PRs.
 * Use "[Squash and merge](https://github.com/blog/2141-squash-your-commits)" to merge PRs.
 * Delete branches for merged PRs (by core devs pushing to the main repo).
+* Make sure commit messages to master are meaningful. For example, remove irrelevant
+  intermediate commit messages.