diff --git a/validator_client/validator_services/src/block_service.rs b/validator_client/validator_services/src/block_service.rs
index 24c9ba5945..1f9197ec35 100644
--- a/validator_client/validator_services/src/block_service.rs
+++ b/validator_client/validator_services/src/block_service.rs
@@ -51,7 +51,7 @@ pub struct BlockServiceBuilder<S, T, E: EthSpec> {
     beacon_nodes: Option<Arc<BeaconNodeFallback<T, E>>>,
     proposer_nodes: Option<Arc<BeaconNodeFallback<T, E>>>,
     executor: Option<TaskExecutor>,
-    chain_spec: Option<ChainSpec>,
+    chain_spec: Option<Arc<ChainSpec>>,
     graffiti: Option<Graffiti>,
     graffiti_file: Option<GraffitiFile>,
 }
@@ -95,6 +95,11 @@ impl<S: ValidatorStore<E>, T: SlotClock + 'static, E: EthSpec> BlockServiceBuild
         self
     }
 
+    pub fn chain_spec(mut self, chain_spec: Arc<ChainSpec>) -> Self {
+        self.chain_spec = Some(chain_spec);
+        self
+    }
+
     pub fn graffiti(mut self, graffiti: Option<Graffiti>) -> Self {
         self.graffiti = graffiti;
         self
@@ -189,7 +194,7 @@ pub struct Inner<S, T, E: EthSpec> {
     pub beacon_nodes: Arc<BeaconNodeFallback<T, E>>,
     pub proposer_nodes: Option<Arc<BeaconNodeFallback<T, E>>>,
     executor: TaskExecutor,
-    chain_spec: ChainSpec,
+    chain_spec: Arc<ChainSpec>,
     graffiti: Option<Graffiti>,
     graffiti_file: Option<GraffitiFile>,
 }