diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
index e2d734e13..569d2a80c 100644
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@@ -1284,10 +1284,10 @@ def get_winning_crosslink_and_attesting_indices(state: BeaconState,
                                                 epoch: Epoch,
                                                 shard: Shard) -> Tuple[Crosslink, Set[ValidatorIndex]]:
     attestations = [a for a in get_matching_source_attestations(state, epoch) if a.data.crosslink.shard == shard]
-    crosslinks = list(filter(
+    crosslinks = filter(
         lambda c: hash_tree_root(state.current_crosslinks[shard]) in (c.parent_root, hash_tree_root(c)),
         [a.data.crosslink for a in attestations]
-    ))
+    )
     # Winning crosslink has the crosslink data root with the most balance voting for it (ties broken lexicographically)
     winning_crosslink = max(crosslinks, key=lambda c: (
         get_attesting_balance(state, [a for a in attestations if a.data.crosslink == c]), c.data_root