diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 7c229dc785e..5d79ea61aaa 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -965,6 +965,8 @@ class Popen(object):
 
             if isinstance(args, types.StringTypes):
                 args = [args]
+            else:
+                args = list(args)
 
             if shell:
                 args = ["/bin/sh", "-c"] + args