diff --git a/doc/user/project/protected_branches.md b/doc/user/project/protected_branches.md
index ab97ff08123a602fd7877b061d97ccc920f7c745..b0754e743149ba75227cb806de061741b4607e2d 100644
--- a/doc/user/project/protected_branches.md
+++ b/doc/user/project/protected_branches.md
@@ -38,6 +38,8 @@ Administrators can set a default branch protection level in the
 Prerequisite:
 
 - You must have at least the Maintainer role.
+- When granting a group **Allowed to merge** or **Allowed to push** permissions
+  on a protected branch, the group must be added to the project.
 
 To protect a branch: