diff --git a/usr/lib/byobu/disk_io b/usr/lib/byobu/disk_io
index c6c6e02e..5a7e2c1d 100755
--- a/usr/lib/byobu/disk_io
+++ b/usr/lib/byobu/disk_io
@@ -62,7 +62,7 @@ __disk_io() {
 		if [ $t2 -le $t1 ]; then
 			rate=0
 		else
-			[ -r "$cache" ] && read x1 < "$cache" || x1=0
+			[ -r "$cache" ] && read x1 < "$cache"
 			local a1= a2= a3= a4= a5= a6= a7= a8= a9= a10=
 			read a1 a2 a3 a4 a5 a6 a7 a8 a9 a10 other < "/sys/block/$disk/stat"
 			if [ "$i" = "read" ]; then