diff --git a/cc2538-bsl.py b/cc2538-bsl.py
index 2f0370e..9ed1aed 100755
--- a/cc2538-bsl.py
+++ b/cc2538-bsl.py
@@ -1221,7 +1221,7 @@ def cli_setup():
                 raise Exception("NO CRC32 match: Local = 0x%x, "
                                 "Target = 0x%x" % (crc_local, crc_target))
 
-        if args.ieee_address != 0:
+        if args.ieee_address is not None:
             ieee_addr = parse_ieee_address(args.ieee_address)
             mdebug(5, "Setting IEEE address to %s"
                        % (':'.join(['%02x' % b