diff --git a/eth2deposit/settings.py b/eth2deposit/settings.py
index b75e6aa..f31edee 100644
--- a/eth2deposit/settings.py
+++ b/eth2deposit/settings.py
@@ -4,23 +4,21 @@ from typing import Dict, NamedTuple
 class BaseChainSetting(NamedTuple):
     GENESIS_FORK_VERSION: bytes
 
-
-MainnetSetting = BaseChainSetting(
-    GENESIS_FORK_VERSION=bytes.fromhex('00000000'),
-)
-
-
+# Eth2 Mainet setting
+MainnetSetting = BaseChainSetting(GENESIS_FORK_VERSION=bytes.fromhex('00000000'))
 # Eth2 spec v0.11.3 testnet
-WittiSetting = BaseChainSetting(
-    GENESIS_FORK_VERSION=bytes.fromhex('00000113'),
-)
+WittiSetting = BaseChainSetting(GENESIS_FORK_VERSION=bytes.fromhex('00000113'))
+# Eth2 spec v0.12.1 testnet
+AltonaSetting = BaseChainSetting(GENESIS_FORK_VERSION=bytes.fromhex('00000121'))
 
 
 MAINNET = 'mainnet'
 WITTI = 'witti'
+ALTONA = 'altona'
 ALL_CHAINS: Dict[str, BaseChainSetting] = {
     MAINNET: MainnetSetting,
     WITTI: WittiSetting,
+    ALTONA: AltonaSetting,
 }