diff --git a/blocks/card-list/card-list.js b/blocks/card-list/card-list.js
index 043091c7..b16af351 100644
--- a/blocks/card-list/card-list.js
+++ b/blocks/card-list/card-list.js
@@ -89,7 +89,7 @@ export function createFilters(articles, viewAll = false) {
     if (item[tagName]) {
       return item[tagName].replace(/,\s*/g, ',').split(',');
     }
-    return null;
+    return [];
   });
   const keywords = new Set([].concat(...allKeywords));
   keywords.delete('');