diff --git a/IP4Config.go b/IP4Config.go
index 242e0f0..5848151 100644
--- a/IP4Config.go
+++ b/IP4Config.go
@@ -222,6 +222,9 @@ func (c *ip4Config) GetPropertyRouteData() ([]IP4RouteData, error) {
 				}
 				route.Metric = uint8(metric)
 			default:
+				if route.AdditionalAttributes == nil {
+					route.AdditionalAttributes = make(map[string]string)
+				}
 				route.AdditionalAttributes[routeDataAttributeName] = routeDataAttribute.String()
 			}
 		}
diff --git a/IP6Config.go b/IP6Config.go
index 8f46acd..88a914a 100644
--- a/IP6Config.go
+++ b/IP6Config.go
@@ -160,6 +160,9 @@ func (c *ip6Config) GetPropertyRouteData() ([]IP6RouteData, error) {
 				}
 				route.Metric = uint8(metric)
 			default:
+				if route.AdditionalAttributes == nil {
+					route.AdditionalAttributes = make(map[string]string)
+				}
 				route.AdditionalAttributes[routeDataAttributeName] = routeDataAttribute.String()
 			}
 		}