diff --git a/check_http_json.py b/check_http_json.py
index c5b7960..94f4fac 100755
--- a/check_http_json.py
+++ b/check_http_json.py
@@ -497,6 +497,7 @@ if __name__ == "__main__" and len(sys.argv) >= 2 and sys.argv[1] == 'UnitTest':
         key_threshold_critical = None
         key_value_list_critical = None
         key_value_list_not_critical = None
+        key_value_list_unknown = None
         key_list_critical = None
         metric_list = None