diff --git a/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate.py b/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate.py
index 4be6737e2..bd52ce727 100644
--- a/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate.py
+++ b/tests/core/pyspec/eth2spec/test/altair/block_processing/sync_aggregate/test_process_sync_aggregate.py
@@ -29,13 +29,10 @@ from eth2spec.test.context import (
 @always_bls
 def test_invalid_signature_bad_domain(spec, state):
     committee_indices = compute_committee_indices(spec, state, state.current_sync_committee)
-    rng = random.Random(2020)
-    random_participant = rng.choice(committee_indices)
 
     block = build_empty_block_for_next_slot(spec, state)
-    # Exclude one participant whose signature was included.
     block.body.sync_aggregate = spec.SyncAggregate(
-        sync_committee_bits=[index != random_participant for index in committee_indices],
+        sync_committee_bits=[True] * len(committee_indices),
         sync_committee_signature=compute_aggregate_sync_committee_signature(
             spec,
             state,