diff --git a/miio/airqualitymonitor.py b/miio/airqualitymonitor.py
index 7a99ae0b2..4ce8098dc 100644
--- a/miio/airqualitymonitor.py
+++ b/miio/airqualitymonitor.py
@@ -8,7 +8,7 @@
 class AirQualityMonitorStatus:
     """Container of air quality monitor status."""
     def __init__(self, data):
-        # {'power': 'on', 'aqi': 34, 'battery': 100, 'usb_state': 'off'}
+        # {'power': 'on', 'aqi': 34, 'battery': 100, 'usb_state': 'off', 'time_state': 'on'}
         self.data = data
 
     @property
@@ -37,9 +37,9 @@ def battery(self) -> int:
         return self.data["battery"]
 
     @property
-    def time_state(self) -> str:
+    def time_state(self) -> bool:
         """Current time state."""
-        return self.data["time_state"]
+        return self.data["time_state"] == "on"
 
     def __repr__(self) -> str:
         s = "<AirQualityMonitorStatus power=%s, " \
diff --git a/miio/tests/test_airqualitymonitor.py b/miio/tests/test_airqualitymonitor.py
index 20c41f9c3..b47d56995 100644
--- a/miio/tests/test_airqualitymonitor.py
+++ b/miio/tests/test_airqualitymonitor.py
@@ -12,7 +12,7 @@ def __init__(self, *args, **kwargs):
             'aqi': 34,
             'battery': 100,
             'usb_state': 'off',
-            'time_state': 'format unknown'
+            'time_state': 'on'
         }
         self.return_values = {
             'get_prop': self._get_state,
@@ -57,5 +57,5 @@ def test_status(self):
         assert self.is_on() is True
         assert self.state().aqi == self.device.start_state["aqi"]
         assert self.state().battery == self.device.start_state["battery"]
-        assert self.state().usb_power == (self.device.start_state["usb_state"] == 'on')
-        assert self.state().time_state == self.device.start_state["time_state"]
+        assert self.state().usb_power is (self.device.start_state["usb_state"] == 'on')
+        assert self.state().time_state is (self.device.start_state["time_state"] == 'on')