diff --git a/src/documents/models.py b/src/documents/models.py
index 8e0435647..cd4517a3d 100755
--- a/src/documents/models.py
+++ b/src/documents/models.py
@@ -230,6 +230,7 @@ class Document(models.Model):
 
     @property
     def file_type(self):
+        # TODO: this is not stable across python versions
         return mimetypes.guess_extension(str(self.mime_type))
 
     @property