diff --git a/eth2/types/src/chain_spec.rs b/eth2/types/src/chain_spec.rs
index fff61186f1..00efdbfe3e 100644
--- a/eth2/types/src/chain_spec.rs
+++ b/eth2/types/src/chain_spec.rs
@@ -257,7 +257,6 @@ impl ChainSpec {
             network_id: 2, // lighthouse testnet network id
             boot_nodes,
             eth1_follow_distance: 16,
-            milliseconds_per_slot: 6_000,
             ..ChainSpec::mainnet()
         }
     }