diff --git a/node_external_ip_controller_async.py b/node_external_ip_controller_async.py
index 1e6bcaf..51a78f9 100644
--- a/node_external_ip_controller_async.py
+++ b/node_external_ip_controller_async.py
@@ -5,7 +5,7 @@ import os
 # Configuration
 import yaml
 
-GATEWAY_SERVICES_FILE = os.getenv("GATEWAY_SERVICES_FILE")
+GATEWAY_SERVICES_FILE = os.getenv("GATEWAY_SERVICES_FILE", "gateway_services.yaml")
 with open(GATEWAY_SERVICES_FILE, "r") as f:
     gateway_services = yaml.safe_load(f)