diff --git a/miio/airpurifier.py b/miio/airpurifier.py
index 345fa0f4b..5e899dc20 100644
--- a/miio/airpurifier.py
+++ b/miio/airpurifier.py
@@ -1,6 +1,5 @@
 import logging
 import enum
-import math
 from typing import Any, Dict, Optional
 from collections import defaultdict
 from .device import Device