diff --git a/spiffworkflow-backend/poetry.lock b/spiffworkflow-backend/poetry.lock
index b22d24664..312890e5d 100644
--- a/spiffworkflow-backend/poetry.lock
+++ b/spiffworkflow-backend/poetry.lock
@@ -1824,8 +1824,8 @@ lxml = "*"
 [package.source]
 type = "git"
 url = "https://github.com/sartography/SpiffWorkflow"
-reference = "450ef3bcd639b6bc1c115fbe35bf3f93946cb0c7"
-resolved_reference = "450ef3bcd639b6bc1c115fbe35bf3f93946cb0c7"
+reference = "main"
+resolved_reference = "98c6294f1240aee599cd98bcee58d121cb57b331"
 
 [[package]]
 name = "SQLAlchemy"
@@ -2204,7 +2204,7 @@ testing = ["flake8 (<5)", "func-timeout", "jaraco.functools", "jaraco.itertools"
 [metadata]
 lock-version = "1.1"
 python-versions = ">=3.9,<3.12"
-content-hash = "95c08ed2de5b5d047474666c9e9a5ff3e7e94e6184649c2aa6d3a961711f14b0"
+content-hash = "b16e8fb0cf991bcba08c3ef1ddf205f5899c622a10c79a7f50fb55a36d53b179"
 
 [metadata.files]
 alabaster = [
diff --git a/spiffworkflow-backend/pyproject.toml b/spiffworkflow-backend/pyproject.toml
index 9f8a29443..cbf0b7ade 100644
--- a/spiffworkflow-backend/pyproject.toml
+++ b/spiffworkflow-backend/pyproject.toml
@@ -27,9 +27,7 @@ flask-marshmallow = "*"
 flask-migrate = "*"
 flask-restful = "*"
 werkzeug = "*"
-# temporarily switch off main to fix CI because poetry export doesn't capture the revision if it's not here (it ignores the lock)
-# SpiffWorkflow = {git = "https://github.com/sartography/SpiffWorkflow", rev = "main"}
-SpiffWorkflow = {git = "https://github.com/sartography/SpiffWorkflow", rev = "450ef3bcd639b6bc1c115fbe35bf3f93946cb0c7"}
+SpiffWorkflow = {git = "https://github.com/sartography/SpiffWorkflow", rev = "main"}
 # SpiffWorkflow = {develop = true, path = "../SpiffWorkflow" }
 sentry-sdk = "^1.10"
 sphinx-autoapi = "^2.0"
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 18a61071e..7cec48a19 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 9f2f26bf4..540a0e12c 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 6f20f560b..af2c20340 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 28312f577..50f64a76a 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>