diff --git a/static/img_javascript/ex-3-13-sol.png b/static/img_javascript/ex-3-13-sol.png
new file mode 100644
index 000000000..f704a36e4
Binary files /dev/null and b/static/img_javascript/ex-3-13-sol.png differ
diff --git a/xml/chapter3/section3/subsection1.xml b/xml/chapter3/section3/subsection1.xml
index ed023d843..eef18c8d8 100644
--- a/xml/chapter3/section3/subsection1.xml
+++ b/xml/chapter3/section3/subsection1.xml
@@ -832,6 +832,17 @@ list_ref(z, 100);
+
+ (provided by GitHub user jonathantorres)
+ If we try to compute last_pair(z), the
+ program will enter in a infinite loop, since the end of the list points back
+ to the beginning.
+
+
+
+