diff --git a/source/modules/MoreOnMutability.rst b/source/modules/MoreOnMutability.rst
index e3ccd6b..f54daa3 100644
--- a/source/modules/MoreOnMutability.rst
+++ b/source/modules/MoreOnMutability.rst
@@ -174,9 +174,9 @@ You get a new list every time the function is called
 
 For more reading.
 
-This: http://python.net/crew/mwh/hacks/objectthink.html#question
+This: https://groups.google.com/g/comp.lang.python/c/trPUxIWxVnA/m/RiqXEo3pIYkJ
 
-Is a link to a discussion on comp.lang.python from over 15 years ago -- but the issues are still the same. In particular, Alex Martelli's answer is brilliant.
+Is a link to a discussion on comp.lang.python from over 20 years ago -- but the issues are still the same. In particular, Alex Martelli's answer is brilliant.
 
 Go read it....