diff --git a/pywebsrv.py b/pywebsrv.py
index 85c2350..b4e3645 100644
--- a/pywebsrv.py
+++ b/pywebsrv.py
@@ -160,7 +160,7 @@ class FileHandler:
                         return value
                     return value
         if option == "block-ua":
-            return []
+            return [], []
         return None
 
     def read_new_config(self, option, host=None):