diff --git a/raspi_master.yaml b/raspi_master.yaml
index ef48f15..928388a 100644
--- a/raspi_master.yaml
+++ b/raspi_master.yaml
@@ -59,6 +59,16 @@ steps:
       __OTHER_APT_ENABLE__
     unless: rootfs_unpacked
 
+  - copy-file: /etc/initramfs-tools/hooks/rpi-resizerootfs
+    src: rootfs/etc/initramfs-tools/hooks/rpi-resizerootfs
+    perm: 0755
+    unless: rootfs_unpacked
+
+  - copy-file: /etc/initramfs-tools/scripts/local-bottom/rpi-resizerootfs
+    src: rootfs/etc/initramfs-tools/scripts/local-bottom/rpi-resizerootfs
+    perm: 0755
+    unless: rootfs_unpacked
+
   - chroot: /
     shell: |
       apt-get update
@@ -97,10 +107,9 @@ steps:
       mkdir -p "${ROOT?}/etc/systemd/system/basic.target.requires/"
       ln -s /etc/systemd/system/rpi-set-sysconf.service "${ROOT?}/etc/systemd/system/basic.target.requires/rpi-set-sysconf.service"
 
-      install -m 755 -o root -g root rootfs/usr/sbin/rpi-resizerootfs "${ROOT?}/usr/sbin/rpi-resizerootfs"
-      install -m 644 -o root -g root rootfs/etc/systemd/system/rpi-resizerootfs.service "${ROOT?}/etc/systemd/system/"
-      mkdir -p "${ROOT?}/etc/systemd/system/systemd-remount-fs.service.requires/"
-      ln -s /etc/systemd/system/rpi-resizerootfs.service "${ROOT?}/etc/systemd/system/systemd-remount-fs.service.requires/rpi-resizerootfs.service"
+      # Resize script is now in the initrd for first boot; no need to ship it.
+      rm -f "${ROOT?}/etc/initramfs-tools/hooks/rpi-resizerootfs"
+      rm -f "${ROOT?}/etc/initramfs-tools/scripts/local-bottom/rpi-resizerootfs"
 
       install -m 644 -o root -g root rootfs/etc/systemd/system/rpi-reconfigure-raspi-firmware.service "${ROOT?}/etc/systemd/system/"
       mkdir -p "${ROOT?}/etc/systemd/system/multi-user.target.requires/"
diff --git a/rootfs/etc/initramfs-tools/hooks/rpi-resizerootfs b/rootfs/etc/initramfs-tools/hooks/rpi-resizerootfs
new file mode 100755
index 0000000..f20edb2
--- /dev/null
+++ b/rootfs/etc/initramfs-tools/hooks/rpi-resizerootfs
@@ -0,0 +1,23 @@
+#!/bin/sh
+set -e
+
+#
+# List the soft prerequisites here.  This is a space separated list of
+# names, of scripts that are in the same directory as this one, that
+# must be run before this one can be.
+#
+PREREQS=""
+case $1 in
+    prereqs) echo "$PREREQS"; exit 0;;
+esac
+
+. /usr/share/initramfs-tools/hook-functions
+
+# XXX: tail and realpath are included by default, right?
+#copy_exec /usr/bin/realpath
+#copy_exec /usr/bin/tail
+copy_exec /sbin/blkid
+copy_exec /bin/lsblk
+copy_exec /sbin/sfdisk
+copy_exec /sbin/partprobe
+copy_exec /sbin/resize2fs
diff --git a/rootfs/etc/initramfs-tools/scripts/local-bottom/rpi-resizerootfs b/rootfs/etc/initramfs-tools/scripts/local-bottom/rpi-resizerootfs
new file mode 100755
index 0000000..8bfdae5
--- /dev/null
+++ b/rootfs/etc/initramfs-tools/scripts/local-bottom/rpi-resizerootfs
@@ -0,0 +1,50 @@
+#!/bin/sh
+set -e
+
+#
+# List the soft prerequisites here.  This is a space separated list of
+# names, of scripts that are in the same directory as this one, that
+# must be run before this one can be.
+#
+PREREQS=""
+case $1 in
+    prereqs) echo "$PREREQS"; exit 0;;
+esac
+
+. /scripts/functions
+
+# Given the root partition, get the underlying device and partition number
+rootpart=$(realpath $ROOT)
+rootpart_nr=$(blkid -sPART_ENTRY_NUMBER -o value -p $rootpart)
+rootdev="/dev/$(lsblk -no pkname "$rootpart")"
+
+# Check if there's free space on the device (note: we align the first
+# partition at 4MB, so there's always at least 3MB free)
+free_space="$(sfdisk -qF $rootdev | tail -n1 | grep -v [^0-9]3M)"
+if test -z "$free_space"; then
+    # Great, we already resized; nothing left to do!
+    exit 0
+fi
+
+log_begin_msg "$0 resizing $ROOT"
+
+# Unmount for safety
+umount "${rootmnt}"
+
+# Expand the partition size to fill the entire device
+sfdisk -f $rootdev -N $rootpart_nr <<EOF
+,+
+EOF
+
+wait_for_udev 5
+
+# Now resize the filesystem
+partprobe $rootdev
+resize2fs $rootpart
+
+# Remount root
+if ! mount -r ${FSTYPE:+-t "${FSTYPE}"} ${ROOTFLAGS} "${ROOT}" "${rootmnt?}"; then
+    panic "Failed to mount ${ROOT} as root file system."
+fi
+
+log_end_msg
diff --git a/rootfs/etc/systemd/system/rpi-resizerootfs.service b/rootfs/etc/systemd/system/rpi-resizerootfs.service
deleted file mode 100644
index 089aecc..0000000
--- a/rootfs/etc/systemd/system/rpi-resizerootfs.service
+++ /dev/null
@@ -1,13 +0,0 @@
-[Unit]
-Description=resize root file system
-Before=local-fs-pre.target
-DefaultDependencies=no
-
-[Service]
-Type=oneshot
-TimeoutSec=infinity
-ExecStart=/usr/sbin/rpi-resizerootfs
-ExecStart=/bin/systemctl --no-reload disable %n
-
-[Install]
-RequiredBy=local-fs-pre.target
diff --git a/rootfs/usr/sbin/rpi-resizerootfs b/rootfs/usr/sbin/rpi-resizerootfs
deleted file mode 100755
index 124f342..0000000
--- a/rootfs/usr/sbin/rpi-resizerootfs
+++ /dev/null
@@ -1,22 +0,0 @@
-#!/bin/sh
-
-rootpart="$(findmnt -n -o SOURCE /)"
-rootdev="/dev/$(lsblk -no pkname "$rootpart")"
-
-flock $rootdev sfdisk -f $rootdev -N 2 <<EOF
-,+
-EOF
-
-sleep 5
-
-udevadm settle
-
-sleep 5
-
-flock $rootdev partprobe $rootdev
-
-mount -o remount,rw $rootpart
-
-resize2fs $rootpart
-
-exit 0