diff --git a/quartz/plugins/transformers/frontmatter.ts b/quartz/plugins/transformers/frontmatter.ts
index 296a6c56b..4f951b0ba 100644
--- a/quartz/plugins/transformers/frontmatter.ts
+++ b/quartz/plugins/transformers/frontmatter.ts
@@ -115,9 +115,8 @@ export const FrontMatter: QuartzTransformerPlugin<Partial<Options>> = (userOpts)
             if (socialImage) data.socialImage = socialImage
 
             // Remove duplicate slugs
-            const uniqueSlugs = [...new Set(allSlugs)]
-            allSlugs.length = 0
-            uniqueSlugs.forEach((slug) => allSlugs.push(slug))
+            const uniqueSlugs = [...new Set(allSlugs)];
+						allSlugs.splice(0, allSlugs.length, ...uniqueSlugs);
 
             // fill in frontmatter
             file.data.frontmatter = data as QuartzPluginData["frontmatter"]