diff --git a/components/site/test_site/templates/category.html b/components/site/test_site/templates/category.html
index 842f6e2d..f7904310 100644
--- a/components/site/test_site/templates/category.html
+++ b/components/site/test_site/templates/category.html
@@ -1,8 +1,5 @@
-Category: {{ category.name }}
+{% extends "sample/templates/category.html" %}
 
-
-{% for page in category.pages %}
-    <article>
-        <h3 class="post__title"><a href="{{ page.permalink }}">{{ page.title }}</a></h3>
-    </article>
-{% endfor %}
+{% block extra_category %}
+EXTENDED
+{% endblock extra_category %}
diff --git a/components/site/test_site/themes/sample/templates/category.html b/components/site/test_site/themes/sample/templates/category.html
new file mode 100644
index 00000000..7a016ae2
--- /dev/null
+++ b/components/site/test_site/themes/sample/templates/category.html
@@ -0,0 +1,11 @@
+Category: {{ category.name }}
+
+
+{% for page in category.pages %}
+    <article>
+        <h3 class="post__title"><a href="{{ page.permalink }}">{{ page.title }}</a></h3>
+    </article>
+{% endfor %}
+
+{% block extra_category %}
+{% endblock extra_category %}
diff --git a/components/site/tests/site.rs b/components/site/tests/site.rs
index bf1d4e26..659304b3 100644
--- a/components/site/tests/site.rs
+++ b/components/site/tests/site.rs
@@ -223,6 +223,8 @@ fn can_build_site_with_categories() {
     assert!(file_exists!(public, "categories/index.html"));
     assert!(file_exists!(public, "categories/a/index.html"));
     assert!(file_exists!(public, "categories/b/index.html"));
+    // Extending from a theme works
+    assert!(file_contains!(public, "categories/a/index.html", "EXTENDED"));
     // Tags aren't
     assert_eq!(file_exists!(public, "tags/index.html"), false);