diff --git a/specs/phase1/beacon-chain.md b/specs/phase1/beacon-chain.md
index e782573c3..e04c22f42 100644
--- a/specs/phase1/beacon-chain.md
+++ b/specs/phase1/beacon-chain.md
@@ -1084,7 +1084,7 @@ def process_light_client_committee_updates(state: BeaconState) -> None:
     """
     Update light client committees.
     """
-    next_epoch = compute_epoch_at_slot(state.slot + 1)
+    next_epoch = compute_epoch_at_slot(Slot(state.slot + 1))
     if next_epoch % LIGHT_CLIENT_COMMITTEE_PERIOD == 0:
         state.current_light_committee = state.next_light_committee
         new_committee = get_light_client_committee(state, next_epoch + LIGHT_CLIENT_COMMITTEE_PERIOD)