diff --git a/pages/search/[keyword].js b/pages/search/[keyword].js
index 74591872..1607cb90 100644
--- a/pages/search/[keyword].js
+++ b/pages/search/[keyword].js
@@ -107,8 +107,8 @@ async function filterByMemCache(allPosts, keyword) {
   for (const post of allPosts) {
     const cacheKey = 'page_block_' + post.id
     const page = await getDataFromCache(cacheKey)
-    const tagContent = post.tags ? post.tags.join(' ') : ''
-    const categoryContent = post.category ? post.category.join(' ') : ''
+    const tagContent = post.tags && Array.isArray(post.tags) ? post.tags.join(' ') : ''
+    const categoryContent = post.category && Array.isArray(post.category) ? post.category.join(' ') : ''
     const articleInfo = post.title + post.summary + tagContent + categoryContent
     let hit = articleInfo.indexOf(keyword) > -1
     let indexContent = [post.summary]