diff --git a/sharepoint_browser.py b/sharepoint_browser.py
index cfa9770..173d838 100644
--- a/sharepoint_browser.py
+++ b/sharepoint_browser.py
@@ -1892,7 +1892,7 @@ class SharePointApp(wx.Frame):
         except RuntimeError:
             pass
 
-    def _fetch_list_contents_bg(self, data, nav_gen=0):
+    def _fetch_list_contents_bg(self, data, nav_gen=None):
         if not self.ensure_valid_token(): return
         self.pulse_gauge(True)
         items_data = []
@@ -1973,9 +1973,9 @@ class SharePointApp(wx.Frame):
             self.list_ctrl.SetItem(idx, 2, size_str)
             self.list_ctrl.SetItem(idx, 3, item['modified'])
 
-    def _finalize_list_loading(self, items_data, nav_gen=0):
+    def _finalize_list_loading(self, items_data, nav_gen=None):
         if not self: return
-        if nav_gen != self._nav_gen:
+        if nav_gen is not None and nav_gen != self._nav_gen:
             return  # User navigated away; discard stale results
         self.current_items = items_data
         self.apply_sorting()