diff --git a/beacon_node/src/config.rs b/beacon_node/src/config.rs
index 6b700259f..6b9490a29 100644
--- a/beacon_node/src/config.rs
+++ b/beacon_node/src/config.rs
@@ -357,6 +357,13 @@ fn init_new_client<E: EthSpec>(
 
     let spec = &mut eth2_config.spec;
 
+    // For now, assume that all networks will use the lighthouse genesis fork.
+    spec.genesis_fork = Fork {
+        previous_version: [0, 0, 0, 0],
+        current_version: [1, 3, 3, 7],
+        epoch: Epoch::new(0),
+    };
+
     client_config.eth1.deposit_contract_address =
         format!("{:?}", eth2_testnet_config.deposit_contract_address()?);
     client_config.eth1.deposit_contract_deploy_block =
diff --git a/lcli/src/deploy_deposit_contract.rs b/lcli/src/deploy_deposit_contract.rs
index 7ae0b3362..f40849c35 100644
--- a/lcli/src/deploy_deposit_contract.rs
+++ b/lcli/src/deploy_deposit_contract.rs
@@ -5,7 +5,7 @@ use eth2_testnet_config::Eth2TestnetConfig;
 use std::fs::File;
 use std::io::Read;
 use std::path::PathBuf;
-use types::{ChainSpec, EthSpec, YamlConfig};
+use types::{ChainSpec, Epoch, EthSpec, Fork, YamlConfig};
 use web3::{transports::Http, Web3};
 
 pub const SECONDS_PER_ETH1_BLOCK: u64 = 15;
@@ -130,6 +130,12 @@ pub fn lighthouse_testnet_spec(mut spec: ChainSpec) -> ChainSpec {
     // With a follow distance of 16, this is 40mins.
     spec.seconds_per_day = SECONDS_PER_ETH1_BLOCK * spec.eth1_follow_distance * 2 * 5;
 
+    spec.genesis_fork = Fork {
+        previous_version: [0, 0, 0, 0],
+        current_version: [1, 3, 3, 7],
+        epoch: Epoch::new(0),
+    };
+
     spec
 }
 
diff --git a/lcli/src/eth1_genesis.rs b/lcli/src/eth1_genesis.rs
index 4b06d2c11..576843ced 100644
--- a/lcli/src/eth1_genesis.rs
+++ b/lcli/src/eth1_genesis.rs
@@ -5,7 +5,7 @@ use futures::Future;
 use genesis::{Eth1Config, Eth1GenesisService};
 use std::path::PathBuf;
 use std::time::Duration;
-use types::EthSpec;
+use types::{Epoch, EthSpec, Fork};
 
 /// Interval between polling the eth1 node for genesis information.
 pub const ETH1_GENESIS_UPDATE_INTERVAL: Duration = Duration::from_millis(7_000);
@@ -28,7 +28,7 @@ pub fn run<T: EthSpec>(mut env: Environment<T>, matches: &ArgMatches) -> Result<
     let mut eth2_testnet_config: Eth2TestnetConfig<T> =
         Eth2TestnetConfig::load(testnet_dir.clone())?;
 
-    let spec = eth2_testnet_config
+    let mut spec = eth2_testnet_config
         .yaml_config
         .as_ref()
         .ok_or_else(|| "The testnet directory must contain a spec config".to_string())?
@@ -40,6 +40,12 @@ pub fn run<T: EthSpec>(mut env: Environment<T>, matches: &ArgMatches) -> Result<
             )
         })?;
 
+    spec.genesis_fork = Fork {
+        previous_version: [0, 0, 0, 0],
+        current_version: [1, 3, 3, 7],
+        epoch: Epoch::new(0),
+    };
+
     let mut config = Eth1Config::default();
     config.endpoint = endpoint.to_string();
     config.deposit_contract_address = eth2_testnet_config.deposit_contract_address.clone();