diff --git a/exercises/practice/perfect-numbers/.meta/config.json b/exercises/practice/perfect-numbers/.meta/config.json
index a30cdfdd..55f716f2 100644
--- a/exercises/practice/perfect-numbers/.meta/config.json
+++ b/exercises/practice/perfect-numbers/.meta/config.json
@@ -20,5 +20,5 @@
   },
   "blurb": "Determine if a number is perfect, abundant, or deficient based on Nicomachus' (60 - 120 CE) classification scheme for positive integers.",
   "source": "Taken from Chapter 2 of Functional Thinking by Neal Ford.",
-  "source_url": "https://www.oreilly.com/library/view/functional-thinking/9781449365509/"
+  "source_url": "https://nealford.com/books/functionalthinking.html"
 }