diff --git a/boards/models/attachment/__init__.py b/boards/models/attachment/__init__.py
--- a/boards/models/attachment/__init__.py
+++ b/boards/models/attachment/__init__.py
@@ -53,11 +53,11 @@ class Attachment(models.Model):
         file_viewer = None
         for viewer in get_viewers():
             if viewer.supports(self.mimetype):
-                file_viewer = viewer(self.file, self.mimetype)
+                file_viewer = viewer
                 break
         if file_viewer is None:
-            file_viewer = AbstractViewer(self.file, self.mimetype)
+            file_viewer = AbstractViewer
 
-        return file_viewer.get_view()
+        return file_viewer(self.file, self.mimetype).get_view()