diff --git a/consensus/types/src/beacon_state.rs b/consensus/types/src/beacon_state.rs
index 0a3d768c59..1bd4927fe8 100644
--- a/consensus/types/src/beacon_state.rs
+++ b/consensus/types/src/beacon_state.rs
@@ -592,6 +592,7 @@ where
     #[compare_fields(as_iter)]
     #[test_random(default)]
     #[superstruct(only(Fulu, Gloas))]
+    #[serde(with = "ssz_types::serde_utils::quoted_u64_fixed_vec")]
     pub proposer_lookahead: Vector<u64, E::ProposerLookaheadSlots>,
 
     // Gloas