diff --git a/Makefile b/Makefile
index cef4bc6cb..fb4af334a 100644
--- a/Makefile
+++ b/Makefile
@@ -77,7 +77,7 @@ test:
 	$(MAKE) codetest
 
 offlinetest: codetest
-	$(PYTHON) -m pytest -k "not download"
+	$(PYTHON) -m pytest -Werror -m "not download"
 
 CODE_FOLDERS_CMD = find yt_dlp -type f -name '__init__.py' | sed 's,/__init__.py,,' | grep -v '/__' | sort
 CODE_FOLDERS != $(CODE_FOLDERS_CMD)