diff --git a/app/controllers/attachments_controller.rb b/app/controllers/attachments_controller.rb
index 571374468..2efe1df09 100644
--- a/app/controllers/attachments_controller.rb
+++ b/app/controllers/attachments_controller.rb
@@ -14,7 +14,7 @@ class AttachmentsController < ApplicationController
       update_downloads(@file)
       redirect_to @file.cloud_url and return
     end
-    send_file absolute_path(local_path(@file)), type: @file.content_type
+    send_file absolute_path(local_path(@file)), type: @file.content_type.presence || 'application/octet-stream'
 
     update_downloads(@file)
   end