diff --git a/code-ch06/op.py b/code-ch06/op.py
index 7c17be32..4e563de9 100644
--- a/code-ch06/op.py
+++ b/code-ch06/op.py
@@ -278,7 +278,7 @@ def op_2over(stack):
 def op_2rot(stack):
     if len(stack) < 6:
         return False
-    stack.extend(stack[-6:-4])
+    stack[:] = stack[:-6] + stack[-4:] + stack[-6:-4]
     return True