diff --git a/hooks/pre-auto-gc b/hooks/pre-auto-gc
index c4107f51..ec29be43 100755
--- a/hooks/pre-auto-gc
+++ b/hooks/pre-auto-gc
@@ -29,7 +29,7 @@ then
 	exit 0
 fi
 
-if test -x /sbin/on_ac_power && /sbin/on_ac_power
+if test -x /sbin/on_ac_power && (/sbin/on_ac_power;test $? -ne 1)
 then
 	exit 0
 elif test "$(cat /sys/class/power_supply/AC/online 2>/dev/null)" = 1