diff --git a/docs/index.rst b/docs/index.rst
index 30493fa4..e319b563 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -42,6 +42,12 @@ with a permissive `MIT license <https://github.com/mpusz/units/blob/master/LICEN
     reference/customization_points
     reference/systems
 
+.. note::
+
+    Source code documentation tools used to generate the above chapter still do not understand
+    C++20 to well which results in some issues in the generated output. We do our best to address
+    this ASAP.
+
 .. toctree::
     :maxdepth: 1
     :caption: Appendix: