diff --git a/pipenv/patched/contoml/file/file.py b/pipenv/patched/contoml/file/file.py
index 16017b9971..99ce1483e6 100755
--- a/pipenv/patched/contoml/file/file.py
+++ b/pipenv/patched/contoml/file/file.py
@@ -231,7 +231,7 @@ def has_anonymous_entry():
         if has_anonymous_entry():
             return items
         else:
-            return items + [('', self[''])]
+            return list(items) + [('', self[''])]
 
     @property
     def primitive(self):