diff --git a/README.md b/README.md
index f03046d..b402a6a 100644
--- a/README.md
+++ b/README.md
@@ -85,9 +85,9 @@ devAddr = [0x00, 0x00, 0x00, 0x00]
 nwkSKey = [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
 appSKey = [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
 
-devAddr_hex = " ".join(list(map(lambda x: "{0:02x}".format(x), devAddr))).upper()
-nwkSKey_hex = " ".join(list(map(lambda x: "{0:02x}".format(x), nwkSKey))).upper()
-appSKey_hex = " ".join(list(map(lambda x: "{0:02x}".format(x), appSKey))).upper()
+devAddr_hex = " ".join(["%02X" % (x,) for x in devAddr])
+nwkSKey_hex = " ".join(["%02X" % (x,) for x in nwkSKey])
+appSKey_hex = " ".join(["%02X" % (x,) for x in appSKey])
 print("devAddr: ", devAddr_hex)
 print("nwkSKey: ", nwkSKey_hex)
 print("appSKey: ", appSKey_hex)