--- a/src/Doc/System/Sessions.thy Mon Feb 12 13:27:30 2018 +0100
+++ b/src/Doc/System/Sessions.thy Mon Feb 12 14:13:54 2018 +0100
@@ -154,7 +154,7 @@
although it uses relatively complex quasi-hierarchic naming conventions like
\<^verbatim>\<open>HOL-SPARK\<close>, \<^verbatim>\<open>HOL-SPARK-Examples\<close>. An alternative is to use unqualified
names that are relatively long and descriptive, as in the Archive of Formal
- Proofs (\<^url>\<open>http://afp.sourceforge.net\<close>), for example.
+ Proofs (\<^url>\<open>https://isa-afp.org\<close>), for example.
\<close>