diff --git a/lib/manager/git-submodules/readme.md b/lib/manager/git-submodules/readme.md
index 93fc4c2c7779171876fd65197dffbec237ce6d4a..2f2eb75ff6ddb799b71c97ca025f02e5c3a983d5 100644
--- a/lib/manager/git-submodules/readme.md
+++ b/lib/manager/git-submodules/readme.md
@@ -1 +1,4 @@
-Keeps Git submodules updated within a repository.
+Keeps publicly accessible Git submodules updated within a repository.
+
+Renovate does not support updating Git submodules that are hosted on a private repository.
+Subscribe to [issue #10149 on GitHub](https://github.com/renovatebot/renovate/issues/10149) to keep track of our progress towards supporting private Git submodules.