diff --git a/projects/forms.py b/projects/forms.py
index 173d65e..e4daf9c 100644
--- a/projects/forms.py
+++ b/projects/forms.py
@@ -95,6 +95,9 @@ def update(self, po, *, request):
             if not msgid_with_context:
                 continue
 
+            # Better be safe than sorry -- do not modify the entries in
+            # self.entries, find the entry in the current version of the pofile
+            # instead.
             for entry in po:
                 if entry.msgid_with_context == msgid_with_context:
                     old = copy.deepcopy(entry)