diff --git a/cfg_checker/modules/network/mapper.py b/cfg_checker/modules/network/mapper.py
index fd47918..02c5fa6 100644
--- a/cfg_checker/modules/network/mapper.py
+++ b/cfg_checker/modules/network/mapper.py
@@ -346,6 +346,7 @@
                     # in case of manual and dhcp, no check possible
                     _gate = "-"
                     _d_gate = "-"
+                    _d_gate_str = "-"
                 # iterate through interfaces
                 _a = _runtime[network][hostname]
                 for _host in _a: