diff --git a/_config.yml b/_config.yml
index e5d4e8d..004f14b 100644
--- a/_config.yml
+++ b/_config.yml
@@ -35,7 +35,7 @@ exclude:
   - assets/vendor/selectivizr/tests
   - assets/vendor/clipboard/test
 
-gems:
+plugins:
   - jekyll-sitemap
   - jekyll-redirect-from
   - jekyll-seo-tag
diff --git a/appendix.md b/appendix.md
index 316c6bd..09c6e45 100644
--- a/appendix.md
+++ b/appendix.md
@@ -25,7 +25,7 @@ If you're here to choose a license, **[start from the home page](/)** to see a f
     {% endfor %}
   {% endfor %}
 </tr>
-{% assign licenses = site.licenses sort: "path" %}
+{% assign licenses = site.licenses | sort: "path" %}
 {% for license in licenses %}
   <tr style="height: 3em"><th scope="row"><a href="{{ license.id }}">{{ license.title }}</a></th>
   {% assign seen_tags = '' %}