diff --git a/src/main.rs b/src/main.rs
index c159c25..e5017b7 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -19,7 +19,7 @@ struct User {
     username: String,
     email: Option<String>,
     display_name: Option<String>,
-    created_at: String,  // ISO 8601 formatted date string
+    created_at: chrono::DateTime<chrono::Utc>,
 }
 
 impl User {
@@ -29,7 +29,7 @@ impl User {
             username,
             email,
             display_name,
-            created_at: chrono::Utc::now().to_rfc3339(),
+            created_at: chrono::Utc::now(),
         }
     }
 }