diff --git a/gatsby-node.js b/gatsby-node.js
index f3084861..a70e9aec 100644
--- a/gatsby-node.js
+++ b/gatsby-node.js
@@ -6,6 +6,7 @@ function sourceNodes({ actions, createNodeId, createContentDigest }) {
   people
     .sort(() => Math.random() - 0.5)
     .forEach(p => {
+      // Remove duplicated tags.
       const person = { ...p, tags: [...new Set(p.tags)] };
       const nodeMeta = {
         id: createNodeId(`person-${person.name}`),
diff --git a/src/util/stats.js b/src/util/stats.js
index 862cf86b..f016702d 100644
--- a/src/util/stats.js
+++ b/src/util/stats.js
@@ -3,8 +3,9 @@ import people from '../data.js';
 
 function merge(prop) {
   return function(acc, obj) {
-    const propEntries = [...new Set(obj[prop])];
-    return [...propEntries, ...acc];
+    // Remove duplicated values.
+    const values = [...new Set(obj[prop])];
+    return [...values, ...acc];
   };
 }