diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 44d563e8fa..eb73d46a13 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -85,8 +85,8 @@ $ git commit
 The commit message should describe what changed and why.
 
 1. The first line should:
-   - contain a short description of the change
-   - be 50 characters or less
+   - contain a short description of the change (preferably 50 characters or less,
+     and no more than 72 characters)
    - be entirely in lowercase with the exception of proper nouns, acronyms, and
    the words that refer to code, like function/variable names
    - be prefixed with the name of the changed subsystem and start with an