diff --git a/contribute/tags_and_branches.html b/contribute/tags_and_branches.html
index 8c59ae7266..44fbba2033 100644
--- a/contribute/tags_and_branches.html
+++ b/contribute/tags_and_branches.html
@@ -195,6 +195,8 @@ <h3 id="leanprover-communitymathlib4-aka-mathlib" class="markdown-heading"><code
 </li>
 </ul>
 </li>
+<li>The <code>nightly-testing-*</code> and <code>bump/v4*</code> branches are write protected,
+so may only be modified via PRs, maintainers, or the relevant bots.</li>
 <li>Note that the <code>nightly-testing</code> branch of Mathlib may use the <code>nightly-testing</code> branch of Std as required.</li>
 <li>Similarly a <code>bump/v4.X.0</code> branch of Mathlib may use the <code>bump/v4.X.0</code> branch of Std as required.</li>
 <li>Branches <code>lean-pr-testing-NNNN</code> are automatically created for any Lean PR that passes CI,