diff --git a/prompt.bash b/prompt.bash
index edfb833..b8d9751 100644
--- a/prompt.bash
+++ b/prompt.bash
@@ -160,7 +160,11 @@ git_branch_color()
 battery()
 {
     command -v acpi >/dev/null 2>&1 || { echo -n ""; return; }
-    bat=`acpi --battery | sed "s/^Battery .*, \([0-9]*\)%.*$/\1/"`
+    bat=`acpi --battery 2>/dev/null | sed "s/^Battery .*, \([0-9]*\)%.*$/\1/"`
+    if [ "${bat}x" == "x" ] ; then
+	echo -n ""
+	return
+    fi
     if [ ${bat} -lt 90 ] ; then
         echo -n " ${bat}%"
     else