diff --git a/openlp/core/ui/servicemanager.py b/openlp/core/ui/servicemanager.py
index f758a85ee..c05c31243 100644
--- a/openlp/core/ui/servicemanager.py
+++ b/openlp/core/ui/servicemanager.py
@@ -646,17 +646,17 @@ class ServiceManager(QtWidgets.QWidget, RegistryBase, Ui_ServiceManager, LogMixi
         for local_file_item, zip_file_item in write_list:
             total_size += local_file_item.stat().st_size
         self.log_debug('ServiceManager.save_file - ZIP contents size is %i bytes' % total_size)
-        self.main_window.display_progress_bar(total_size)
+        self.main_window.display_progress_bar(1000)
         try:
             with NamedTemporaryFile(dir=str(file_path.parent), prefix='.') as temp_file, \
                     zipfile.ZipFile(temp_file, 'w') as zip_file:
                 # First we add service contents..
                 zip_file.writestr('service_data.osj', service_content)
-                self.main_window.increment_progress_bar(service_content_size)
+                self.main_window.increment_progress_bar(service_content_size / total_size * 1000)
                 # Finally add all the listed media files.
                 for local_file_item, zip_file_item in write_list:
                     zip_file.write(str(local_file_item), str(zip_file_item))
-                    self.main_window.increment_progress_bar(local_file_item.stat().st_size)
+                    self.main_window.increment_progress_bar(local_file_item.stat().st_size / total_size * 1000)
                 with suppress(FileNotFoundError):
                     file_path.unlink()
                 os.link(temp_file.name, file_path)
diff --git a/tests/functional/openlp_core/ui/test_servicemanager.py b/tests/functional/openlp_core/ui/test_servicemanager.py
index 87574be4b..33655bb20 100644
--- a/tests/functional/openlp_core/ui/test_servicemanager.py
+++ b/tests/functional/openlp_core/ui/test_servicemanager.py
@@ -655,6 +655,43 @@ def test_save_file_raises_permission_error(mocked_os, mocked_save_file_as, mocke
     mocked_save_file_as.assert_called_with()
 
 
+@patch('openlp.core.ui.servicemanager.zipfile')
+@patch('openlp.core.ui.servicemanager.ServiceManager.save_file_as')
+@patch('openlp.core.ui.servicemanager.os')
+@patch('openlp.core.ui.servicemanager.len')
+def test_save_file_large_file(mocked_len, mocked_os, mocked_save_file_as, mocked_zipfile, registry):
+    """
+    Test that when a file size size larger than a 32bit signed int is attempted to save, the progress bar
+    should be provided a value that fits in a 32bit int (because it's passed to C++ as a 32bit unsigned int)
+    """
+    # GIVEN: A service manager, a service to save, and len() returns a huge value (file size)
+    def check_for_i32_overflow(val):
+        if val > 2147483647:
+            raise OverflowError
+    mocked_main_window = MagicMock()
+    mocked_main_window.display_progress_bar.side_effect = check_for_i32_overflow
+    Registry().register('main_window', mocked_main_window)
+    Registry().register('application', MagicMock())
+    mocked_settings = MagicMock()
+    Registry().register('settings', mocked_settings)
+    service_manager = ServiceManager(None)
+    service_manager._service_path = MagicMock()
+    service_manager._save_lite = False
+    service_manager.service_items = []
+    service_manager.service_theme = 'Default'
+    service_manager.service_manager_list = MagicMock()
+    mocked_save_file_as.return_value = True
+    mocked_zipfile.ZipFile.return_value = MagicMock()
+    mocked_len.return_value = 10000000000000
+
+    # WHEN: The service is saved and no error is raised
+    result = service_manager.save_file()
+
+    # THEN: The "save_as" method is called to save the service
+    assert result is True
+    mocked_save_file_as.assert_called_with()
+
+
 @patch('openlp.core.ui.servicemanager.ServiceManager.regenerate_service_items')
 def test_theme_change_global(mocked_regenerate_service_items, registry):
     """