diff --git a/src/lean_spec/subspecs/chain/config.py b/src/lean_spec/subspecs/chain/config.py
index 7ce34f2a..f5b1319c 100644
--- a/src/lean_spec/subspecs/chain/config.py
+++ b/src/lean_spec/subspecs/chain/config.py
@@ -18,8 +18,8 @@
 SECONDS_PER_SLOT: Final = SLOT_DURATION_MS // 1000
 """The fixed duration of a single slot in seconds."""
 
-SLOTS_PER_EPOCH: Final = 96
-"""The number of slots in an epoch."""
+JUSTIFICATION_LOOKBACK_SLOTS: Final = 3
+"""The number of slots to lookback for justification."""
 
 PROPOSER_REORG_CUTOFF_BPS: Final = 2500
 """
@@ -81,7 +81,7 @@ class _ChainConfig(BaseModel):
     # Time Parameters
     slot_duration_ms: Uint64
     second_per_slot: Uint64
-    slots_per_epoch: Uint64
+    justification_lookback_slots: Uint64
     proposer_reorg_cutoff_bps: BasisPoint
     vote_due_bps: BasisPoint
     fast_confirm_due_bps: BasisPoint
@@ -96,7 +96,7 @@ class _ChainConfig(BaseModel):
 DEVNET_CONFIG: Final = _ChainConfig(
     slot_duration_ms=SLOT_DURATION_MS,
     second_per_slot=SECONDS_PER_SLOT,
-    slots_per_epoch=SLOTS_PER_EPOCH,
+    justification_lookback_slots=JUSTIFICATION_LOOKBACK_SLOTS,
     proposer_reorg_cutoff_bps=PROPOSER_REORG_CUTOFF_BPS,
     vote_due_bps=VOTE_DUE_BPS,
     fast_confirm_due_bps=FAST_CONFIRM_DUE_BPS,
diff --git a/src/lean_spec/subspecs/networking/gossipsub.py b/src/lean_spec/subspecs/networking/gossipsub.py
index d1ebeb85..02a4e865 100644
--- a/src/lean_spec/subspecs/networking/gossipsub.py
+++ b/src/lean_spec/subspecs/networking/gossipsub.py
@@ -39,10 +39,12 @@ class GossipsubParameters(StrictBaseModel):
     """The number of history windows to gossip about."""
 
     seen_ttl_secs: int = (
-        DEVNET_CONFIG.second_per_slot * DEVNET_CONFIG.slots_per_epoch * 2
+        DEVNET_CONFIG.second_per_slot
+        * DEVNET_CONFIG.justification_lookback_slots
+        * 2
     )
     """
     The expiry time in seconds for the cache of seen message IDs.
 
-    This is calculated as SECONDS_PER_SLOT * SLOTS_PER_EPOCH * 2.
+    This is calculated as SECONDS_PER_SLOT * JUSTIFICATION_LOOKBACK_SLOTS * 2.
     """