diff --git a/runtime/doc/if_pyth.txt b/runtime/doc/if_pyth.txt
index d1dc845..8f96e41 100644
--- a/runtime/doc/if_pyth.txt
+++ b/runtime/doc/if_pyth.txt
@@ -715,6 +715,8 @@
 functions to evaluate Python expressions and pass their values to Vim script.
 |pyxeval()| is also available.
 
+The Python value "None" is converted to v:none.
+
 ==============================================================================
 9. Dynamic loading					*python-dynamic*