diff --git a/rpi3-resizerootfs b/rpi3-resizerootfs
index 32c861c..37a0b40 100755
--- a/rpi3-resizerootfs
+++ b/rpi3-resizerootfs
@@ -4,10 +4,20 @@ roottmp=$(lsblk -l -o MAJ:MIN,MOUNTPOINT | grep '/$')
 rootpart=/dev/block/${roottmp% /}
 rootdev=${rootpart%:*}:0
 
-sfdisk -f $rootdev -N 2 <<EOF
+flock $rootdev sfdisk -f $rootdev -N 2 <<EOF
 ,+
 EOF
 
-partprobe
+sleep 5
+
+udevadm settle
+
+sleep 5
+
+flock $rootdev partprobe $rootdev
+
+mount -o remount,rw $rootpart
 
 resize2fs $rootpart
+
+exit 0
diff --git a/rpi3-resizerootfs.service b/rpi3-resizerootfs.service
index e90252e..131955e 100644
--- a/rpi3-resizerootfs.service
+++ b/rpi3-resizerootfs.service
@@ -5,6 +5,7 @@ DefaultDependencies=no
 
 [Service]
 Type=oneshot
+TimeoutSec=600
 ExecStart=/usr/sbin/rpi3-resizerootfs
 ExecStart=/bin/systemctl --no-reload disable %n