diff --git a/beacon_node/beacon_chain/test_harness/src/harness.rs b/beacon_node/beacon_chain/test_harness/src/harness.rs
index ee4d94148..0b493b64a 100644
--- a/beacon_node/beacon_chain/test_harness/src/harness.rs
+++ b/beacon_node/beacon_chain/test_harness/src/harness.rs
@@ -19,7 +19,7 @@ pub struct BeaconChainHarness {
     pub block_store: Arc<BeaconBlockStore<MemoryDB>>,
     pub state_store: Arc<BeaconStateStore<MemoryDB>>,
     pub validators: Vec<TestValidator>,
-    pub spec: ChainSpec,
+    pub spec: Arc<ChainSpec>,
 }
 
 impl BeaconChainHarness {
@@ -74,12 +74,14 @@ impl BeaconChainHarness {
             .unwrap(),
         );
 
+        let spec = Arc::new(spec);
+
         debug!("Creating validator producer and attester instances...");
 
         // Spawn the test validator instances.
         let validators: Vec<TestValidator> = keypairs
-            .par_iter()
-            .map(|keypair| TestValidator::new(keypair.clone(), beacon_chain.clone(), &spec))
+            .iter()
+            .map(|keypair| TestValidator::new(keypair.clone(), beacon_chain.clone(), spec.clone()))
             .collect();
 
         debug!("Created {} TestValidators", validators.len());
diff --git a/beacon_node/beacon_chain/test_harness/src/validator/mod.rs b/beacon_node/beacon_chain/test_harness/src/validator/mod.rs
index 08da1d197..018ffbc86 100644
--- a/beacon_node/beacon_chain/test_harness/src/validator/mod.rs
+++ b/beacon_node/beacon_chain/test_harness/src/validator/mod.rs
@@ -52,9 +52,8 @@ impl TestValidator {
     pub fn new(
         keypair: Keypair,
         beacon_chain: Arc<BeaconChain<MemoryDB, TestingSlotClock>>,
-        spec: &ChainSpec,
+        spec: Arc<ChainSpec>,
     ) -> Self {
-        let spec = Arc::new(spec.clone());
         let slot_clock = Arc::new(TestingSlotClock::new(spec.genesis_slot));
         let signer = Arc::new(TestSigner::new(keypair.clone()));
         let beacon_node = Arc::new(BenchingBeaconNode::new(beacon_chain.clone()));