diff --git a/bin/ream/assets/lean/sample_spec.yml b/bin/ream/assets/lean/sample_spec.yml
index 36f64dc91..173221934 100644
--- a/bin/ream/assets/lean/sample_spec.yml
+++ b/bin/ream/assets/lean/sample_spec.yml
@@ -1,3 +1,4 @@
 SECONDS_PER_SLOT: 12
 GENESIS_TIME: 0
+JUSTIFICATION_LOOKBACK_SLOTS: 3
 NUM_VALIDATORS: 4
diff --git a/crates/common/network_spec/src/networks/lean.rs b/crates/common/network_spec/src/networks/lean.rs
index 28c9d6d86..dfed7d4a7 100644
--- a/crates/common/network_spec/src/networks/lean.rs
+++ b/crates/common/network_spec/src/networks/lean.rs
@@ -12,6 +12,7 @@ pub static LEAN_NETWORK_SPEC: OnceLock<Arc<LeanNetworkSpec>> = OnceLock::new();
 #[serde(rename_all = "UPPERCASE")]
 pub struct LeanNetworkSpec {
     pub genesis_time: u64,
+    pub justification_lookback_slots: u64,
     pub seconds_per_slot: u64,
     pub num_validators: u64,
 }
@@ -27,6 +28,7 @@ impl LeanNetworkSpec {
 
         Arc::new(Self {
             genesis_time: current_timestamp + 3,
+            justification_lookback_slots: 3,
             seconds_per_slot: 4,
             num_validators: 4,
         })
diff --git a/crates/networking/p2p/src/gossipsub/lean/configurations.rs b/crates/networking/p2p/src/gossipsub/lean/configurations.rs
index daa79a3ee..05284c3e2 100644
--- a/crates/networking/p2p/src/gossipsub/lean/configurations.rs
+++ b/crates/networking/p2p/src/gossipsub/lean/configurations.rs
@@ -1,7 +1,6 @@
 use std::time::Duration;
 
 use libp2p::gossipsub::{Config, ConfigBuilder, MessageId, ValidationMode};
-use ream_consensus_misc::constants::beacon::SLOTS_PER_EPOCH;
 use ream_network_spec::networks::lean_network_spec;
 use sha2::{Digest, Sha256};
 
@@ -31,7 +30,9 @@ impl Default for LeanGossipsubConfig {
             .history_gossip(3)
             .max_messages_per_rpc(Some(500))
             .duplicate_cache_time(Duration::from_secs(
-                SLOTS_PER_EPOCH * lean_network_spec().seconds_per_slot * 2,
+                lean_network_spec().justification_lookback_slots
+                    * lean_network_spec().seconds_per_slot
+                    * 2,
             ))
             .validate_messages()
             .validation_mode(ValidationMode::Anonymous)