diff --git a/src/Object/Api/Mastodon/Account.php b/src/Object/Api/Mastodon/Account.php
index 358ad4aded..01febcf363 100644
--- a/src/Object/Api/Mastodon/Account.php
+++ b/src/Object/Api/Mastodon/Account.php
@@ -108,7 +108,7 @@ class Account extends BaseDataTransferObject
 		$userContactCreated = $userContact['created'] ?? DBA::NULL_DATETIME;
 
 		$created = $userContactCreated < $publicContactCreated && ($userContactCreated != DBA::NULL_DATETIME) ? $userContactCreated : $publicContactCreated;
-		$this->created_at      = DateTimeFormat::utc($created, DateTimeFormat::ATOM);
+		$this->created_at      = DateTimeFormat::utc($created, DateTimeFormat::API);
 
 		$this->note            = BBCode::convert($publicContact['about'], false);
 		$this->url             = $publicContact['url'];
diff --git a/src/Object/Api/Mastodon/Notification.php b/src/Object/Api/Mastodon/Notification.php
index ee4930e3cd..2c2e8d6f9c 100644
--- a/src/Object/Api/Mastodon/Notification.php
+++ b/src/Object/Api/Mastodon/Notification.php
@@ -52,7 +52,7 @@ class Notification extends BaseDataTransferObject
 	{
 		$this->id         = (string)$id;
 		$this->type       = $type;
-		$this->created_at = DateTimeFormat::utc($created_at, DateTimeFormat::ATOM);
+		$this->created_at = DateTimeFormat::utc($created_at, DateTimeFormat::API);
 		$this->account    = $account->toArray();
 
 		if (!empty($status)) {
diff --git a/src/Object/Api/Mastodon/Status.php b/src/Object/Api/Mastodon/Status.php
index 974ac0dc74..f236d2231d 100644
--- a/src/Object/Api/Mastodon/Status.php
+++ b/src/Object/Api/Mastodon/Status.php
@@ -100,7 +100,7 @@ class Status extends BaseDataTransferObject
 	public function __construct(array $item, Account $account, Counts $counts, UserAttributes $userAttributes, bool $sensitive, Application $application, array $mentions, array $tags, Card $card, array $attachments, array $reblog)
 	{
 		$this->id         = (string)$item['uri-id'];
-		$this->created_at = DateTimeFormat::utc($item['created'], DateTimeFormat::ATOM);
+		$this->created_at = DateTimeFormat::utc($item['created'], DateTimeFormat::API);
 
 		if ($item['gravity'] == GRAVITY_COMMENT) {
 			$this->in_reply_to_id         = (string)$item['thr-parent-id'];
diff --git a/src/Object/Api/Mastodon/Token.php b/src/Object/Api/Mastodon/Token.php
index 1c78d69593..dfd5de0e95 100644
--- a/src/Object/Api/Mastodon/Token.php
+++ b/src/Object/Api/Mastodon/Token.php
@@ -53,6 +53,6 @@ class Token extends BaseDataTransferObject
 		$this->access_token = $access_token;
 		$this->token_type   = $token_type;
 		$this->scope        = $scope;
-		$this->created_at   = DateTimeFormat::utc($created_at, DateTimeFormat::ATOM);
+		$this->created_at   = DateTimeFormat::utc($created_at, DateTimeFormat::API);
 	}
 }
diff --git a/src/Util/DateTimeFormat.php b/src/Util/DateTimeFormat.php
index eefbfcf7bc..d2a96d0357 100644
--- a/src/Util/DateTimeFormat.php
+++ b/src/Util/DateTimeFormat.php
@@ -31,9 +31,10 @@ use Exception;
  */
 class DateTimeFormat
 {
-	const ATOM = 'Y-m-d\TH:i:s\Z';
+	const ATOM  = 'Y-m-d\TH:i:s\Z';
 	const MYSQL = 'Y-m-d H:i:s';
-	const HTTP = 'D, d M Y H:i:s \G\M\T';
+	const HTTP  = 'D, d M Y H:i:s \G\M\T';
+	const API   = 'Y-m-d\TH:i:s.000\Z';
 
 	/**
 	 * convert() shorthand for UTC.