diff --git a/src/spiffworkflow_backend/routes/process_api_blueprint.py b/src/spiffworkflow_backend/routes/process_api_blueprint.py
index e635f885..d8518ddd 100644
--- a/src/spiffworkflow_backend/routes/process_api_blueprint.py
+++ b/src/spiffworkflow_backend/routes/process_api_blueprint.py
@@ -241,7 +241,7 @@ def get_file(process_group_id: str, process_model_id: str, file_name: str) -> An
 def process_model_file_update(
     process_group_id: str, process_model_id: str, file_name: str
 ) -> flask.wrappers.Response:
-    """Process_model_file_save."""
+    """Process_model_file_update."""
     process_model = get_process_model(process_model_id, process_group_id)
 
     request_file = get_file_from_request()
diff --git a/tests/spiffworkflow_backend/integration/test_process_api.py b/tests/spiffworkflow_backend/integration/test_process_api.py
index 50a675a1..c33928d5 100644
--- a/tests/spiffworkflow_backend/integration/test_process_api.py
+++ b/tests/spiffworkflow_backend/integration/test_process_api.py
@@ -3,6 +3,7 @@ import io
 import json
 import time
 from typing import Any
+from conftest import with_db_and_bpmn_file_cleanup
 
 import pytest
 from flask.app import Flask
@@ -39,16 +40,16 @@ class TestProcessApi(BaseTest):
         self, app: Flask, client: FlaskClient, with_db_and_bpmn_file_cleanup: None
     ) -> None:
         """Test_add_new_process_model."""
-        model_id = "sample"
+        process_model_identifier = "sample"
         model_display_name = "Sample"
         model_description = "The sample"
         self.create_process_model_with_api(
             client,
-            process_model_id=model_id,
+            process_model_id=process_model_identifier,
             process_model_display_name=model_display_name,
             process_model_description=model_description,
         )
-        process_model = ProcessModelService().get_process_model(model_id)
+        process_model = ProcessModelService().get_process_model(process_model_identifier)
         assert model_display_name == process_model.display_name
         assert 0 == process_model.display_order
         assert 1 == len(ProcessModelService().get_process_groups())
@@ -63,10 +64,43 @@ class TestProcessApi(BaseTest):
             file_data=bpmn_file_data_bytes,
             process_model=process_model,
         )
-        process_model = ProcessModelService().get_process_model(model_id)
+        process_model = ProcessModelService().get_process_model(process_model_identifier)
         assert process_model.primary_file_name == bpmn_file_name
         assert process_model.primary_process_id == "sample"
 
+    def test_primary_process_id_updates_via_xml(self, app: Flask, client: FlaskClient, with_db_and_bpmn_file_cleanup: None) -> None:
+        process_model_identifier = "sample"
+        initial_primary_process_id = "sample"
+        terminal_primary_process_id = "new_process_id"
+
+        process_model = load_test_spec(process_model_id=process_model_identifier)
+        assert process_model.primary_process_id == initial_primary_process_id
+
+        bpmn_file_name = "sample.bpmn"
+        bpmn_file_data_bytes = self.get_test_data_file_contents(
+            bpmn_file_name, "sample"
+        )
+        bpmn_file_data_string = bpmn_file_data_bytes.decode('utf-8')
+        old_string = f'bpmn:process id="{initial_primary_process_id}"'
+        new_string = f'bpmn:process id="{terminal_primary_process_id}"'
+        updated_bpmn_file_data_string = bpmn_file_data_string.replace(old_string, new_string)
+        updated_bpmn_file_data_bytes = bytearray(updated_bpmn_file_data_string, 'utf-8')
+        data = {"file": (io.BytesIO(updated_bpmn_file_data_bytes), bpmn_file_name)}
+
+        user = self.find_or_create_user()
+        response = client.put(
+            f"/v1.0/process-models/{process_model.process_group_id}/{process_model.id}/files/{bpmn_file_name}",
+            data=data,
+            follow_redirects=True,
+            content_type="multipart/form-data",
+            headers=logged_in_headers(user),
+        )
+        assert response.status_code == 200
+        process_model = ProcessModelService().get_process_model(process_model_identifier)
+        assert process_model.primary_file_name == bpmn_file_name
+        assert process_model.primary_process_id == terminal_primary_process_id
+
+
     def test_process_model_delete(
         self, app: Flask, client: FlaskClient, with_db_and_bpmn_file_cleanup: None
     ) -> None:
@@ -160,11 +194,11 @@ class TestProcessApi(BaseTest):
 
         # add 5 models to the group
         for i in range(5):
-            model_id = f"test_model_{i}"
+            process_model_identifier = f"test_model_{i}"
             model_display_name = f"Test Model {i}"
             model_description = f"Test Model {i} Description"
             self.create_process_model_with_api(
-                client, group_id, model_id, model_display_name, model_description
+                client, group_id, process_model_identifier, model_display_name, model_description
             )
 
         # get all models