diff --git a/spiffworkflow-backend/src/spiffworkflow_backend/services/process_instance_processor.py b/spiffworkflow-backend/src/spiffworkflow_backend/services/process_instance_processor.py
index 18a61071..7cec48a1 100644
--- a/spiffworkflow-backend/src/spiffworkflow_backend/services/process_instance_processor.py
+++ b/spiffworkflow-backend/src/spiffworkflow_backend/services/process_instance_processor.py
@@ -1304,9 +1304,9 @@ class ProcessInstanceProcessor:
                 continue
 
             # timer events are not related to messaging, so ignore them for these purposes
-            if waiting_task.task_spec.event_definition.__class__.__name__ in [
-                "TimerEventDefinition",
-            ]:
+            if waiting_task.task_spec.event_definition.__class__.__name__.endswith(
+                "TimerEventDefinition"
+            ):
                 continue
 
             message_model = MessageModel.query.filter_by(
diff --git a/spiffworkflow-backend/tests/data/process_navigation/process_navigation.bpmn b/spiffworkflow-backend/tests/data/process_navigation/process_navigation.bpmn
index 9f2f26bf..540a0e12 100644
--- a/spiffworkflow-backend/tests/data/process_navigation/process_navigation.bpmn
+++ b/spiffworkflow-backend/tests/data/process_navigation/process_navigation.bpmn
@@ -41,7 +41,7 @@
       <bpmn:incoming>Flow_1vld4r2</bpmn:incoming>
       <bpmn:outgoing>Flow_13ai5vv</bpmn:outgoing>
       <bpmn:timerEventDefinition id="TimerEventDefinition_1fnogr9">
-        <bpmn:timeDuration xsi:type="bpmn:tFormalExpression">timedelta(hours=1)</bpmn:timeDuration>
+        <bpmn:timeDuration xsi:type="bpmn:tFormalExpression">"PT1H"</bpmn:timeDuration>
       </bpmn:timerEventDefinition>
     </bpmn:intermediateCatchEvent>
     <bpmn:manualTask id="Activity_0uum4kq" name="Any Task">
diff --git a/spiffworkflow-backend/tests/data/spiff_example/multiinstance.bpmn b/spiffworkflow-backend/tests/data/spiff_example/multiinstance.bpmn
index 6f20f560..af2c2034 100644
--- a/spiffworkflow-backend/tests/data/spiff_example/multiinstance.bpmn
+++ b/spiffworkflow-backend/tests/data/spiff_example/multiinstance.bpmn
@@ -244,7 +244,7 @@ Order Total: {{ order_total }}
         <bpmn:incoming>Flow_08d8k7v</bpmn:incoming>
         <bpmn:outgoing>Flow_1570y49</bpmn:outgoing>
         <bpmn:timerEventDefinition id="TimerEventDefinition_0hwvz0g">
-          <bpmn:timeDuration xsi:type="bpmn:tFormalExpression">timedelta(seconds=10)</bpmn:timeDuration>
+          <bpmn:timeDuration xsi:type="bpmn:tFormalExpression">"PT10S"</bpmn:timeDuration>
         </bpmn:timerEventDefinition>
       </bpmn:intermediateCatchEvent>
       <bpmn:sequenceFlow id="Flow_1570y49" sourceRef="Event_1lwrxto" targetRef="Activity_1f2e8xi" />
@@ -315,7 +315,7 @@ Order Total: {{ order_total }}
     <bpmn:boundaryEvent id="Event_05ljcvh" name="Order Delayed" cancelActivity="false" attachedToRef="Activity_0gol5af">
       <bpmn:outgoing>Flow_1ny6y69</bpmn:outgoing>
       <bpmn:timerEventDefinition id="TimerEventDefinition_1ll0ob4">
-        <bpmn:timeDuration xsi:type="bpmn:tFormalExpression">timedelta(minutes=1)</bpmn:timeDuration>
+        <bpmn:timeDuration xsi:type="bpmn:tFormalExpression">"PT1M"</bpmn:timeDuration>
       </bpmn:timerEventDefinition>
     </bpmn:boundaryEvent>
     <bpmn:boundaryEvent id="Event_0qk2468" name="Handle Product Unavailable" attachedToRef="Activity_0gol5af">
diff --git a/spiffworkflow-backend/tests/data/timer_intermediate_catch_event/timer_intermediate_catch_event.bpmn b/spiffworkflow-backend/tests/data/timer_intermediate_catch_event/timer_intermediate_catch_event.bpmn
index 28312f57..50f64a76 100644
--- a/spiffworkflow-backend/tests/data/timer_intermediate_catch_event/timer_intermediate_catch_event.bpmn
+++ b/spiffworkflow-backend/tests/data/timer_intermediate_catch_event/timer_intermediate_catch_event.bpmn
@@ -13,7 +13,7 @@
       <bpmn:incoming>Flow_109wuuc</bpmn:incoming>
       <bpmn:outgoing>Flow_0cy1fiy</bpmn:outgoing>
       <bpmn:timerEventDefinition id="TimerEventDefinition_1al5gzu">
-        <bpmn:timeDuration xsi:type="bpmn:tFormalExpression">timedelta(seconds=30)</bpmn:timeDuration>
+        <bpmn:timeDuration xsi:type="bpmn:tFormalExpression">"PT30S"</bpmn:timeDuration>
       </bpmn:timerEventDefinition>
     </bpmn:intermediateCatchEvent>
   </bpmn:process>
diff --git a/spiffworkflow-backend/tests/spiffworkflow_backend/integration/test_process_api.py b/spiffworkflow-backend/tests/spiffworkflow_backend/integration/test_process_api.py
index ef6ce101..f52cbc43 100644
--- a/spiffworkflow-backend/tests/spiffworkflow_backend/integration/test_process_api.py
+++ b/spiffworkflow-backend/tests/spiffworkflow_backend/integration/test_process_api.py
@@ -2755,7 +2755,6 @@ class TestProcessApi(BaseTest):
             content_type="application/json",
             data=json.dumps(data),
         )
-        print(f"response.json: {response.json}")
         assert response.json["status"] == "complete"
 
         response = client.get(