diff --git a/Documentation/contributing/git_commit_messages.md b/Documentation/contributing/git_commit_messages.md
index a007b2a20c..fc53bdb148 100644
--- a/Documentation/contributing/git_commit_messages.md
+++ b/Documentation/contributing/git_commit_messages.md
@@ -47,8 +47,9 @@ to go over everything again. There are other tutorials that cover that.
 
 - Make sure the problem being solved by the commit is described. While
   it may be obvious to the committer, it may not be obvious to others.
-- Reference other commits with either CB:XXXXX or a 10 character hash
-  and the subject.
+- When referencing other commits use a 12 character hash and the subject
+  (e.g. `commit XXXXXXXXXXXX ("some commit")`). However, use `CB:XXXXX`
+  when referring to an open or abandoned change on Gerrit.
 - When using a URL in a commit message, use archive.org when possible.
   URLs often get changed or go stale, so this keeps them stable.
 - Make sure that all changes in a patch are addressed in the commit