--- acpi-1.4/acpi.c.orig	2009-03-23 17:23:12 +0200
+++ acpi-1.4/acpi.c	2009-07-03 10:32:27 +0300
@@ -303,6 +303,8 @@
 		state = value->value;
 	    } else if (!strcmp(value->attr, "voltage_now")) {
 		voltage = get_unit_value(value->value) / 1000;
+			if (!voltage) /* zero voltage makes all calculations mood */
+				voltage = -1;
 	    }
 	    fields = list_next(fields);
 	}