diff --git a/mkdocs_rss_plugin/plugin.py b/mkdocs_rss_plugin/plugin.py
index 7e4a310..c4ab87f 100644
--- a/mkdocs_rss_plugin/plugin.py
+++ b/mkdocs_rss_plugin/plugin.py
@@ -60,6 +60,8 @@ def __init__(self, *args, **kwargs):
         # pages storage
         super().__init__(*args, **kwargs)
 
+        self.cmd_is_serve: bool = False
+
     def on_startup(
         self, *, command: Literal["build", "gh-deploy", "serve"], dirty: bool
     ) -> None: