diff --git a/packages/docusaurus-plugin-content-blog/src/__tests__/index.test.ts b/packages/docusaurus-plugin-content-blog/src/__tests__/index.test.ts
index 9dfe8f93278f..afad6bffc5da 100644
--- a/packages/docusaurus-plugin-content-blog/src/__tests__/index.test.ts
+++ b/packages/docusaurus-plugin-content-blog/src/__tests__/index.test.ts
@@ -57,6 +57,7 @@ describe('loadBlog', () => {
         permalink: noDatePermalink,
         title: 'no date',
       },
+      truncated: false,
     });
     expect(
       blogPosts.find(v => v.metadata.title === 'Happy 1st Birthday Slash!')
@@ -76,6 +77,7 @@ describe('loadBlog', () => {
         permalink: '/blog/2019/01/01/date-matter',
         title: 'date-matter',
       },
+      truncated: false,
     });
 
     expect(
@@ -91,6 +93,7 @@ describe('loadBlog', () => {
         permalink: '/blog/2019/01/01/date-matter',
         title: 'date-matter',
       },
+      truncated: false,
     });
   });
 });
diff --git a/packages/docusaurus-plugin-content-blog/src/blogUtils.ts b/packages/docusaurus-plugin-content-blog/src/blogUtils.ts
index b6f3411302af..35b4bdbdabbe 100644
--- a/packages/docusaurus-plugin-content-blog/src/blogUtils.ts
+++ b/packages/docusaurus-plugin-content-blog/src/blogUtils.ts
@@ -137,7 +137,7 @@ export async function generateBlogPosts(
           date,
           tags: frontMatter.tags,
           title: frontMatter.title,
-          truncated: truncateMarker.test(content),
+          truncated: truncateMarker?.test(content) || false,
         },
       });
     }),