diff --git a/fork_choice_store/src/store.rs b/fork_choice_store/src/store.rs
index 847ea0eb..e7a3c1f5 100644
--- a/fork_choice_store/src/store.rs
+++ b/fork_choice_store/src/store.rs
@@ -1176,7 +1176,6 @@ impl<P: Preset> Store<P> {
         Ok(BlockAction::Accept(chain_link, attester_slashing_results))
     }
 
-    #[expect(clippy::too_many_lines)]
     pub fn validate_aggregate_and_proof<I>(
         &self,
         aggregate_and_proof: Arc<SignedAggregateAndProof<P>>,
@@ -1205,12 +1204,9 @@ impl<P: Preset> Store<P> {
             }
         }
 
-        let AttestationData {
-            slot,
-            index,
-            target,
-            ..
-        } = aggregate.data();
+        let AttestationData { slot, target, .. } = aggregate.data();
+
+        let index = misc::committee_index(&aggregate);
 
         // TODO(feature/deneb): Figure out why this validation is split over 2 methods.
         // TODO(feature/deneb): This appears to be unfinished.
diff --git a/http_api/src/standard.rs b/http_api/src/standard.rs
index 70284e47..6f92ce17 100644
--- a/http_api/src/standard.rs
+++ b/http_api/src/standard.rs
@@ -2912,7 +2912,6 @@ async fn submit_attestation_to_pool<P: Preset, W: Wait>(
     let run = async {
         let AttestationData {
             slot,
-            index: committee_index,
             beacon_block_root,
             target,
             ..
@@ -2931,6 +2930,8 @@ async fn submit_attestation_to_pool<P: Preset, W: Wait>(
         let committees_per_slot =
             accessors::get_committee_count_per_slot(&target_state, relative_epoch);
 
+        let committee_index = misc::committee_index(&attestation);
+
         let subnet_id =
             misc::compute_subnet_for_attestation::<P>(committees_per_slot, slot, committee_index)?;