diff --git a/pybtc/constants.py b/pybtc/constants.py
index 2d6f88c..a9fa7ec 100644
--- a/pybtc/constants.py
+++ b/pybtc/constants.py
@@ -79,6 +79,9 @@ SCRIPT_TYPES = { "P2PKH":        0,
                 }
 
 
-
-PRIVATEWALLETVERSION = b'\x04\x88\xAD\xE4'
-PUBLICWALLETVERSION = b'\x04\x88\xB2\x1E'
+# CONSTANTS hierarchical deterministic wallets (HD Wallets)
+MAINNET_PRIVATE_WALLET_VERSION = b'\x04\x88\xAD\xE4'
+MAINNET_PUBLIC_WALLET_VERSION = b'\x04\x88\xB2\x1E'
+TESTNET_PRIVATE_WALLET_VERSION = b'\x04\x35\x83\x94'
+TESTNET_PUBLIC_WALLET_VERSION = b'\x04\x35\x87\xCF'
+FIRST_HARDENED_CHILD = 0x80000000