diff --git a/consensus/types/src/chain_spec.rs b/consensus/types/src/chain_spec.rs
index 0a1dc5c916..6562dc00ae 100644
--- a/consensus/types/src/chain_spec.rs
+++ b/consensus/types/src/chain_spec.rs
@@ -1019,6 +1019,7 @@ pub struct Config {
     ejection_balance: u64,
     #[serde(with = "serde_utils::quoted_u64")]
     min_per_epoch_churn_limit: u64,
+    #[serde(default)]
     #[serde(with = "serde_utils::quoted_u64")]
     max_per_epoch_activation_churn_limit: u64,
     #[serde(with = "serde_utils::quoted_u64")]