diff --git a/homeassistant/components/miele/fan.py b/homeassistant/components/miele/fan.py
index 4781d27901f..fcd74a93bfb 100644
--- a/homeassistant/components/miele/fan.py
+++ b/homeassistant/components/miele/fan.py
@@ -99,8 +99,10 @@ class MieleFan(MieleEntity, FanEntity):
     @property
     def is_on(self) -> bool:
         """Return current on/off state."""
-        assert self.device.state_ventilation_step is not None
-        return self.device.state_ventilation_step > 0
+        return (
+            self.device.state_ventilation_step is not None
+            and self.device.state_ventilation_step > 0
+        )
 
     @property
     def speed_count(self) -> int:
diff --git a/tests/components/miele/fixtures/fan_devices.json b/tests/components/miele/fixtures/fan_devices.json
index d3403c0f7bc..9904f6f5faa 100644
--- a/tests/components/miele/fixtures/fan_devices.json
+++ b/tests/components/miele/fixtures/fan_devices.json
@@ -210,5 +210,129 @@
       "ecoFeedback": null,
       "batteryLevel": null
     }
+  },
+  "DummyAppliance_74_off": {
+    "ident": {
+      "type": {
+        "key_localized": "Device type",
+        "value_raw": 74,
+        "value_localized": "Hob with vapour extraction"
+      },
+      "deviceName": "",
+      "protocolVersion": 2,
+      "deviceIdentLabel": {
+        "fabNumber": "**REDACTED**",
+        "fabIndex": "00",
+        "techType": "KMDA7473",
+        "matNumber": "",
+        "swids": ["000"]
+      },
+      "xkmIdentLabel": {
+        "techType": "EK039W",
+        "releaseVersion": "02.80"
+      }
+    },
+    "state": {
+      "ProgramID": {
+        "value_raw": 0,
+        "value_localized": "",
+        "key_localized": "Program name"
+      },
+      "status": {
+        "value_raw": 1,
+        "value_localized": "Off",
+        "key_localized": "status"
+      },
+      "programType": {
+        "value_raw": 0,
+        "value_localized": "",
+        "key_localized": "Program type"
+      },
+      "programPhase": {
+        "value_raw": 0,
+        "value_localized": "",
+        "key_localized": "Program phase"
+      },
+      "remainingTime": [0, 0],
+      "startTime": [0, 0],
+      "targetTemperature": [
+        {
+          "value_raw": -32768,
+          "value_localized": null,
+          "unit": "Celsius"
+        },
+        {
+          "value_raw": -32768,
+          "value_localized": null,
+          "unit": "Celsius"
+        },
+        {
+          "value_raw": -32768,
+          "value_localized": null,
+          "unit": "Celsius"
+        }
+      ],
+      "coreTargetTemperature": [
+        {
+          "value_raw": -32768,
+          "value_localized": null,
+          "unit": "Celsius"
+        }
+      ],
+      "temperature": [
+        {
+          "value_raw": -32768,
+          "value_localized": null,
+          "unit": "Celsius"
+        },
+        {
+          "value_raw": -32768,
+          "value_localized": null,
+          "unit": "Celsius"
+        },
+        {
+          "value_raw": -32768,
+          "value_localized": null,
+          "unit": "Celsius"
+        }
+      ],
+      "coreTemperature": [
+        {
+          "value_raw": -32768,
+          "value_localized": null,
+          "unit": "Celsius"
+        }
+      ],
+      "signalInfo": false,
+      "signalFailure": false,
+      "signalDoor": false,
+      "remoteEnable": {
+        "fullRemoteControl": false,
+        "smartGrid": false,
+        "mobileStart": false
+      },
+      "ambientLight": null,
+      "light": null,
+      "elapsedTime": [],
+      "spinningSpeed": {
+        "unit": "rpm",
+        "value_raw": null,
+        "value_localized": null,
+        "key_localized": "Spin speed"
+      },
+      "dryingStep": {
+        "value_raw": null,
+        "value_localized": "",
+        "key_localized": "Drying level"
+      },
+      "ventilationStep": {
+        "value_raw": null,
+        "value_localized": "",
+        "key_localized": "Fan level"
+      },
+      "plateStep": [],
+      "ecoFeedback": null,
+      "batteryLevel": null
+    }
   }
 }
diff --git a/tests/components/miele/snapshots/test_fan.ambr b/tests/components/miele/snapshots/test_fan.ambr
index ffd6c90a388..595d4463462 100644
--- a/tests/components/miele/snapshots/test_fan.ambr
+++ b/tests/components/miele/snapshots/test_fan.ambr
@@ -48,6 +48,55 @@
     'state': 'on',
   })
 # ---
+# name: test_fan_states[fan_devices.json-platforms0][fan.hob_with_extraction_fan_2-entry]
+  EntityRegistryEntrySnapshot({
+    'aliases': set({
+    }),
+    'area_id': None,
+    'capabilities': dict({
+    }),
+    'config_entry_id': <ANY>,
+    'config_subentry_id': <ANY>,
+    'device_class': None,
+    'device_id': <ANY>,
+    'disabled_by': None,
+    'domain': 'fan',
+    'entity_category': None,
+    'entity_id': 'fan.hob_with_extraction_fan_2',
+    'has_entity_name': True,
+    'hidden_by': None,
+    'icon': None,
+    'id': <ANY>,
+    'labels': set({
+    }),
+    'name': None,
+    'options': dict({
+    }),
+    'original_device_class': None,
+    'original_icon': None,
+    'original_name': 'Fan',
+    'platform': 'miele',
+    'previous_unique_id': None,
+    'supported_features': 0,
+    'translation_key': 'fan',
+    'unique_id': 'DummyAppliance_74_off-fan_readonly',
+    'unit_of_measurement': None,
+  })
+# ---
+# name: test_fan_states[fan_devices.json-platforms0][fan.hob_with_extraction_fan_2-state]
+  StateSnapshot({
+    'attributes': ReadOnlyDict({
+      'friendly_name': 'Hob with extraction Fan',
+      'supported_features': <FanEntityFeature: 0>,
+    }),
+    'context': <ANY>,
+    'entity_id': 'fan.hob_with_extraction_fan_2',
+    'last_changed': <ANY>,
+    'last_reported': <ANY>,
+    'last_updated': <ANY>,
+    'state': 'off',
+  })
+# ---
 # name: test_fan_states[fan_devices.json-platforms0][fan.hood_fan-entry]
   EntityRegistryEntrySnapshot({
     'aliases': set({