diff --git a/bumblebee/modules/battery.py b/bumblebee/modules/battery.py
index 4feb5e8..7b95480 100644
--- a/bumblebee/modules/battery.py
+++ b/bumblebee/modules/battery.py
@@ -14,6 +14,12 @@ class Module(bumblebee.module.Module):
 
         return "{:02d}%".format(self._capacity)
 
+    def warning(self):
+        return self._capacity < 20
+
+    def critical(self):
+        return self._capacity < 10
+
     def state(self):
         with open("/sys/class/power_supply/{}/status".format(self._battery)) as f:
             self._status = f.read().strip()