diff --git a/init/resize-rootfs-if-needed.sh b/init/resize-rootfs-if-needed.sh
index 46ae9a4..0fc08c0 100755
--- a/init/resize-rootfs-if-needed.sh
+++ b/init/resize-rootfs-if-needed.sh
@@ -15,7 +15,7 @@ sysfs_xvda="/sys/class/block/xvda"
 
 # if root filesystem use already (almost) the whole dis
 non_rootfs_data=$(( 250 * 1024 * 2 ))
-rootfs_size=$(df --block-size=512 --output=size / | tail -n 1)
+rootfs_size=$(df --block-size=512 --output=size / | tail -n 1 | tr -d ' ')
 if [ $(cat $sysfs_xvda/size) -gt \
        $(( non_rootfs_data + rootfs_size )) ]; then
    echo "root filesystem already at $rootfs_size blocks" >&2