diff --git a/git-update b/git-update
index 6a4b46b0ed..307bda3d6a 100755
--- a/git-update
+++ b/git-update
@@ -69,7 +69,7 @@ def update_repo(repo_name, repo_dir, revision, no_interaction, fetch_args=[], re
         if revision:
             print("Checking out %s in %s" % (revision, repo_name))
             git("fetch", *fetch_args, repository_path=repo_dir)
-            git("checkout", revision, repository_path=repo_dir)
+            git("checkout", "--detach", revision, repository_path=repo_dir)
         else:
             print("Updating branch %s in %s" % (get_branch_name(repo_dir), repo_name))
             git("pull", "--rebase", repository_path=repo_dir)