diff --git a/quartz/plugins/transformers/frontmatter.ts b/quartz/plugins/transformers/frontmatter.ts
index 571aa04..04b1105 100644
--- a/quartz/plugins/transformers/frontmatter.ts
+++ b/quartz/plugins/transformers/frontmatter.ts
@@ -37,6 +37,11 @@ export const FrontMatter: QuartzTransformerPlugin<Partial<Options> | undefined>
               data.tags = data.tag
             }
 
+            // coerce title to string
+            if (data.title) {
+              data.title = data.title.toString()
+            }
+
             if (data.tags && !Array.isArray(data.tags)) {
               data.tags = data.tags
                 .toString()