diff --git a/test_libs/pyspec/eth2spec/test/block_processing/test_process_attestation.py b/test_libs/pyspec/eth2spec/test/block_processing/test_process_attestation.py
index 9491ee001..0dae852f0 100644
--- a/test_libs/pyspec/eth2spec/test/block_processing/test_process_attestation.py
+++ b/test_libs/pyspec/eth2spec/test/block_processing/test_process_attestation.py
@@ -219,6 +219,18 @@ def test_bad_previous_crosslink(state):
     yield from run_attestation_processing(state, attestation, False)
 
 
+@spec_state_test
+def test_inconsistent_bitfields(state):
+    attestation = get_valid_attestation(state, signed=False)
+    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY
+
+    attestation.custody_bitfield = deepcopy(attestation.aggregation_bitfield) + b'\x00'
+
+    sign_attestation(state, attestation)
+
+    yield from run_attestation_processing(state, attestation, False)
+
+
 @spec_state_test
 def test_non_empty_custody_bitfield(state):
     attestation = get_valid_attestation(state, signed=False)