diff --git a/tests/core/pyspec/eth2spec/test/helpers/proposer_slashings.py b/tests/core/pyspec/eth2spec/test/helpers/proposer_slashings.py
index a783d2517..ac0a1cce2 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/proposer_slashings.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/proposer_slashings.py
@@ -73,12 +73,13 @@ def check_proposer_slashing_effect(spec, pre_state, state, slashed_index, block=
 
 
 def get_valid_proposer_slashing(spec, state, random_root=b'\x99' * 32,
-                                slashed_index=None, signed_1=False, signed_2=False):
+                                slashed_index=None, slot=None, signed_1=False, signed_2=False):
     if slashed_index is None:
         current_epoch = spec.get_current_epoch(state)
         slashed_index = spec.get_active_validator_indices(state, current_epoch)[-1]
     privkey = pubkey_to_privkey[state.validators[slashed_index].pubkey]
-    slot = state.slot
+    if slot is None:
+        slot = state.slot
 
     header_1 = spec.BeaconBlockHeader(
         slot=slot,
diff --git a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attester_slashing.py b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attester_slashing.py
index 940bc47fb..b620a7342 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attester_slashing.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_attester_slashing.py
@@ -6,8 +6,10 @@ from eth2spec.test.context import (
     low_balances, misc_balances,
 )
 from eth2spec.test.helpers.attestations import sign_indexed_attestation
-from eth2spec.test.helpers.attester_slashings import get_valid_attester_slashing, \
-    get_indexed_attestation_participants, get_attestation_2_data, get_attestation_1_data
+from eth2spec.test.helpers.attester_slashings import (
+    get_valid_attester_slashing, get_valid_attester_slashing_by_indices,
+    get_indexed_attestation_participants, get_attestation_2_data, get_attestation_1_data,
+)
 from eth2spec.test.helpers.proposer_slashings import get_min_slashing_penalty_quotient
 from eth2spec.test.helpers.state import (
     get_balance,
@@ -126,6 +128,39 @@ def test_success_already_exited_recent(spec, state):
     yield from run_attester_slashing_processing(spec, state, attester_slashing)
 
 
+@with_all_phases
+@spec_state_test
+@always_bls
+def test_success_proposer_index_slashed(spec, state):
+    # Transition past genesis slot because generally doesn't have a proposer
+    next_epoch_via_block(spec, state)
+
+    proposer_index = spec.get_beacon_proposer_index(state)
+    attester_slashing = get_valid_attester_slashing_by_indices(
+        spec, state,
+        [proposer_index],
+        signed_1=True, signed_2=True,
+    )
+
+    yield from run_attester_slashing_processing(spec, state, attester_slashing)
+
+
+@with_all_phases
+@spec_state_test
+def test_success_attestation_from_future(spec, state):
+    # Transition state to future to enable generation of a "future" attestation
+    future_state = state.copy()
+    next_epoch_via_block(spec, future_state)
+    # Generate slashing using the future state
+    attester_slashing = get_valid_attester_slashing(
+        spec, future_state,
+        slot=state.slot + 5,  # Slot is in the future wrt `state`
+        signed_1=True, signed_2=True
+    )
+
+    yield from run_attester_slashing_processing(spec, state, attester_slashing)
+
+
 @with_all_phases
 @with_custom_state(balances_fn=low_balances, threshold_fn=lambda spec: spec.config.EJECTION_BALANCE)
 @spec_test
diff --git a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_proposer_slashing.py b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_proposer_slashing.py
index 48bc5ba3d..6ca87adae 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_proposer_slashing.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_proposer_slashing.py
@@ -55,6 +55,14 @@ def test_success_slashed_and_proposer_index_the_same(spec, state):
     yield from run_proposer_slashing_processing(spec, state, proposer_slashing)
 
 
+@with_all_phases
+@spec_state_test
+def test_success_block_header_from_future(spec, state):
+    proposer_slashing = get_valid_proposer_slashing(spec, state, slot=state.slot + 5, signed_1=True, signed_2=True)
+
+    yield from run_proposer_slashing_processing(spec, state, proposer_slashing)
+
+
 @with_all_phases
 @spec_state_test
 @always_bls