diff --git a/test/unit/attachment_test.rb b/test/unit/attachment_test.rb
index 2bee67ed2..05abc5c63 100644
--- a/test/unit/attachment_test.rb
+++ b/test/unit/attachment_test.rb
@@ -24,6 +24,7 @@ class AttachmentTest < ActiveSupport::TestCase
            :enabled_modules, :issues, :trackers, :attachments
 
   def setup
+    User.current = nil
     set_tmp_attachments_directory
   end