diff --git a/modules/extensions.py b/modules/extensions.py
index 1063e5eb7..17a1d006b 100644
--- a/modules/extensions.py
+++ b/modules/extensions.py
@@ -106,8 +106,8 @@ class Extension:
         self.branch = None
         self.remote = None
         self.have_info_from_repo = False
-        self.mtime = 0
-        self.ctime = 0
+        self.mtime = "2000-01-01T00:00Z"
+        self.ctime = "2000-01-01T00:00Z"
 
     def read_info(self, force=False):
         if self.have_info_from_repo and not force:
diff --git a/modules/ui_extensions.py b/modules/ui_extensions.py
index c9271780e..fa58c0c05 100644
--- a/modules/ui_extensions.py
+++ b/modules/ui_extensions.py
@@ -308,7 +308,7 @@ def create_html(search_text, sort_column):
         ext['enabled'] = installed.enabled if installed is not None else ''
         ext['remote'] = installed.remote if installed is not None else None
         ext['path'] = installed.path if installed is not None else ''
-        ext['sort_default'] = f"{'1' if ext['is_builtin'] else '0'}{'1' if ext['installed'] else '0'}{ext.get('updated', '2000-01-01T00:00')}"
+        ext['sort_default'] = f"{'1' if ext['is_builtin'] else '0'}{'1' if ext['installed'] else '0'}{ext.get('updated', '2000-01-01T00:00Z')}"
     sort_reverse, sort_function = sort_ordering[sort_column]
 
     def dt(x: str):