diff --git a/EIPS/eip-609.md b/EIPS/eip-609.md
index 714a5bde..4ac78781 100644
--- a/EIPS/eip-609.md
+++ b/EIPS/eip-609.md
@@ -18,7 +18,8 @@ This specifies the changes included in the hard fork named Byzantium.
 - Codename: Byzantium
 - Aliases: Metropolis/Byzantium, Metropolis part 1
 - Activation:
-  - Block not specified yet
+  - Block >= 4,370,000 on Mainnet
+  - Block >= 1,700,000 on Ropsten testnet
 - Included EIPs:
   - EIP 100 (Change difficulty adjustment to target mean block time including uncles)
   - EIP 140 (REVERT instruction in the Ethereum Virtual Machine)
@@ -29,6 +30,10 @@ This specifies the changes included in the hard fork named Byzantium.
   - EIP 214 (New opcode STATICCALL)
   - EIP 649 (Difficulty Bomb Delay and Block Reward Reduction)
   - EIP 658 (Embedding transaction return data in receipts)
+  
+## References
+
+1. https://blog.ethereum.org/2017/10/12/byzantium-hf-announcement/
 
 ## Copyright