diff --git a/control/gen-fan-zone-defs.py b/control/gen-fan-zone-defs.py
index 644ce54..e5aa39b 100755
--- a/control/gen-fan-zone-defs.py
+++ b/control/gen-fan-zone-defs.py
@@ -600,7 +600,7 @@
 
     if not args.zone_yaml or not args.fan_yaml:
         parser.print_usage()
-        sys.exit(-1)
+        sys.exit(1)
 
     with open(args.zone_yaml, 'r') as zone_input:
         zone_data = yaml.safe_load(zone_input) or {}