diff --git a/specs/core/0_beacon-chain.md b/specs/core/0_beacon-chain.md
index 01a6ca352..4970a3b00 100644
--- a/specs/core/0_beacon-chain.md
+++ b/specs/core/0_beacon-chain.md
@@ -1615,11 +1615,6 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
         proposer_index=get_beacon_proposer_index(state),
     )
 
-    # Check bitlist lengths
-    committee_size = get_committee_count(state, attestation.data.target.epoch)
-    assert len(attestation.aggregation_bits) == committee_size
-    assert len(attestation.custody_bits) == committee_size
-
     if data.target.epoch == get_current_epoch(state):
         assert data.source == state.current_justified_checkpoint
         parent_crosslink = state.current_crosslinks[data.crosslink.shard]
diff --git a/test_libs/pyspec/eth2spec/test/context.py b/test_libs/pyspec/eth2spec/test/context.py
index 5cc42c510..80edaba9b 100644
--- a/test_libs/pyspec/eth2spec/test/context.py
+++ b/test_libs/pyspec/eth2spec/test/context.py
@@ -10,7 +10,7 @@ from .utils import vector_test, with_meta_tags
 def with_state(fn):
     def entry(*args, **kw):
         try:
-            kw['state'] = create_genesis_state(spec=kw['spec'], num_validators=spec_phase0.SLOTS_PER_EPOCH * 8)
+            kw['state'] = create_genesis_state(spec=kw['spec'], num_validators=spec_phase0.SLOTS_PER_EPOCH * 10)
         except KeyError:
             raise TypeError('Spec decorator must come within state decorator to inject spec into state.')
         return fn(*args, **kw)
diff --git a/test_libs/pyspec/eth2spec/test/phase_1/block_processing/test_process_bit_challenge.py b/test_libs/pyspec/eth2spec/test/phase_1/block_processing/test_process_bit_challenge.py
index e4880555a..ae6ff258c 100644
--- a/test_libs/pyspec/eth2spec/test/phase_1/block_processing/test_process_bit_challenge.py
+++ b/test_libs/pyspec/eth2spec/test/phase_1/block_processing/test_process_bit_challenge.py
@@ -212,13 +212,16 @@ def test_max_reveal_lateness_1(spec, state):
     challenge = get_valid_bit_challenge(spec, state, attestation)
 
     responder_index = challenge.responder_index
+    target_epoch = attestation.data.target.epoch
 
     state.validators[responder_index].max_reveal_lateness = 3
 
-    for i in range(spec.get_randao_epoch_for_custody_period(
-        spec.get_custody_period_for_validator(state, responder_index),
+    latest_reveal_epoch = spec.get_randao_epoch_for_custody_period(
+        spec.get_custody_period_for_validator(state, responder_index, target_epoch),
         responder_index
-    ) + 2 * spec.EPOCHS_PER_CUSTODY_PERIOD + state.validators[responder_index].max_reveal_lateness - 2):
+    ) + 2 * spec.EPOCHS_PER_CUSTODY_PERIOD + state.validators[responder_index].max_reveal_lateness
+
+    while spec.get_current_epoch(state) < latest_reveal_epoch - 2:
         next_epoch(spec, state)
         apply_empty_block(spec, state)