diff --git a/src/index.html b/src/index.html
index b132c799..03b25fb9 100644
--- a/src/index.html
+++ b/src/index.html
@@ -185,8 +185,8 @@ <h2 id="fitness-for-achieving-compliance-with-accessibility-standards">
       to satisfy the Success Criteria, that is, there is no content which
       violates the Success Criteria.
       <cite>
-        <a href="https://www.w3.org/TR/UNDERSTANDING-WCAG20/conformance">Understanding
-          WCAG 2.0: Understanding Conformance</a>
+        <a href="https://www.w3.org/WAI/WCAG21/Understanding/conformance">Understanding
+          WCAG 2.1: Understanding Conformance</a>
       </cite>
     </blockquote>