diff --git a/docs/deprecated.js b/docs/deprecated.js
new file mode 100644
index 000000000..bfb6d128c
--- /dev/null
+++ b/docs/deprecated.js
@@ -0,0 +1,3 @@
+(function ($) {
+  $('#toc-collapse').before('<div class="card" style="background-color: #FF6 !important; padding: 10px; margin: 10px 0;"><h4 style="text-align: center;">ATTENTION</h4><p><strong>These docs are for the old version of farmOS (v1). The latest docs (for v2) are available at <a href="https://docs.farmOS.org">docs.farmOS.org</a>.</strong></p></div>');
+})(jQuery)
diff --git a/mkdocs.yml b/mkdocs.yml
index dee22b631..ae80dc3b8 100644
--- a/mkdocs.yml
+++ b/mkdocs.yml
@@ -65,6 +65,8 @@ nav:
 theme: sandstone
 extra_css:
   - extra.css
+extra_javascript:
+  - deprecated.js
 markdown_extensions:
   - toc:
       permalink: true