diff --git a/lib/Service/ApiService.php b/lib/Service/ApiService.php
index bae813649a1..4244127e232 100644
--- a/lib/Service/ApiService.php
+++ b/lib/Service/ApiService.php
@@ -118,7 +118,7 @@ public function fetch($documentId, $sessionId, $sessionToken) {
 			} catch (NotFoundException $e) {
 				return new NotFoundResponse();
 			}
-			return new FileDisplayResponse($file);
+			return new FileDisplayResponse($file, 200, ['Content-Type' => 'text/plain']);
 		}
 		return new NotFoundResponse();
 	}