diff --git a/usbexec.py b/usbexec.py
index 770b1d62..2bdd157c 100644
--- a/usbexec.py
+++ b/usbexec.py
@@ -112,7 +112,7 @@ def command(self, request_data, response_length):
 
   def execute(self, response_length, *args):
     cmd = str()
-    for i in range(len(args)):
+    for i in enumerate(args):
       if isinstance(args[i], (int, long)):
         cmd += struct.pack('<%s' % self.cmd_arg_type(), args[i])
       elif isinstance(args[i], basestring) and i == len(args) - 1: