diff --git a/packages/testing/src/consensus_testing/test_fixtures/state_transition.py b/packages/testing/src/consensus_testing/test_fixtures/state_transition.py
index 3637c1a47..fccac8c5f 100644
--- a/packages/testing/src/consensus_testing/test_fixtures/state_transition.py
+++ b/packages/testing/src/consensus_testing/test_fixtures/state_transition.py
@@ -116,7 +116,7 @@ def generate(self) -> StateTransitionFixture:
 
                 if cached_state is not None:
                     state = cached_state
-                elif block_spec.skip_slot_processing:
+                elif block_spec.skip_slot_processing and not block_spec.check_state_transition:
                     state = spec.process_block(state, block)
                 else:
                     state = spec.state_transition(state, block=block)
diff --git a/packages/testing/src/consensus_testing/test_types/block_spec.py b/packages/testing/src/consensus_testing/test_types/block_spec.py
index c08d36b8e..ea317b86f 100644
--- a/packages/testing/src/consensus_testing/test_types/block_spec.py
+++ b/packages/testing/src/consensus_testing/test_types/block_spec.py
@@ -71,6 +71,9 @@ class BlockSpec(CamelModel):
     skip_slot_processing: bool = False
     """Skip automatic slot advancement before processing, to exercise slot-mismatch failures."""
 
+    check_state_transition: bool = False
+    """Call `state_transition` after block is generated by `_build_block_from_spec`."""
+
     def resolve_proposer_index(self, num_validators: int) -> ValidatorIndex:
         """Return the proposer index, falling back to the spec's round-robin schedule."""
         if self.proposer_index is not None:
diff --git a/tests/consensus/lstar/state_transition/test_slot_monotonicity.py b/tests/consensus/lstar/state_transition/test_slot_monotonicity.py
index 46d2fe368..99970eba6 100644
--- a/tests/consensus/lstar/state_transition/test_slot_monotonicity.py
+++ b/tests/consensus/lstar/state_transition/test_slot_monotonicity.py
@@ -39,7 +39,11 @@ def test_process_slots_target_equal_to_state_slot_rejected(
     state_transition_test(
         pre=pre_state,
         blocks=[
-            BlockSpec(slot=Slot(1)),
+            BlockSpec(
+                slot=Slot(1),
+                skip_slot_processing=True,
+                check_state_transition=True,
+            ),
         ],
         post=None,
         expected_rejection=ExpectedRejection(