diff --git a/homeassistant/components/sensor/synologydsm.py b/homeassistant/components/sensor/synologydsm.py
index 2b443738230802..0d5a253483f9ac 100644
--- a/homeassistant/components/sensor/synologydsm.py
+++ b/homeassistant/components/sensor/synologydsm.py
@@ -230,6 +230,9 @@ def state(self):
                 attr = getattr(
                     self._api.storage, self.var_id)(self.monitor_device)
 
+                if attr is None:
+                    return None
+
                 if self._api.temp_unit == TEMP_CELSIUS:
                     return attr