diff --git a/lib/AppConfig.php b/lib/AppConfig.php
index cbbe46b475..6261afc752 100644
--- a/lib/AppConfig.php
+++ b/lib/AppConfig.php
@@ -209,6 +209,7 @@ public function getMimeTypes(): array {
 		return array_merge(
 			Capabilities::MIMETYPES,
 			Capabilities::MIMETYPES_MSOFFICE,
+			Capabilities::MIMETYPES_OPTIONAL,
 		);
 	}