diff --git a/bumblebee/modules/battery-upower.py b/bumblebee/modules/battery-upower.py
index 24efecf..f3d59ba 100644
--- a/bumblebee/modules/battery-upower.py
+++ b/bumblebee/modules/battery-upower.py
@@ -240,7 +240,7 @@ class Module(bumblebee.engine.Module):
 
     def state(self, widget):
         state = []
-        capacity = widget.get("capacity")
+        capacity = widget.get("capacity", -1)
         if capacity < 0:
             return ["critical", "unknown"]