diff --git a/checks/check_snmp_synology.py b/checks/check_snmp_synology.py
index 65c321e..3d15fe3 100755
--- a/checks/check_snmp_synology.py
+++ b/checks/check_snmp_synology.py
@@ -595,7 +595,7 @@ class SNMPSynologyRaidStatusContext(nagiosplugin.Context):
     def evaluate(self, metric, resource):
         if metric.value['status'] in ['12', '18']:
             return self.result_cls(nagiosplugin.Critical, "critical", metric)
-        elif metric.value['status'] in range(2,21):
+        elif 2 <= metric.value['status'] <= 21:
             return self.result_cls(nagiosplugin.Warn, "warning", metric)
         elif metric.value['status'] == '1':
             return self.result_cls(nagiosplugin.Ok, "ok", metric)