diff --git a/args.py b/args.py
index 3dc07f4..b04169e 100644
--- a/args.py
+++ b/args.py
@@ -358,7 +358,7 @@ def not_files(self):
     def copy(self):
         """Returns a copy of Args object for temporary manipulation."""
 
-        return ArgsList(self.all)
+        return ArgsList(self.all[:])
 
     @property
     def assignments(self):