diff --git a/README.md b/README.md
index dd9ef78..42409b6 100644
--- a/README.md
+++ b/README.md
@@ -55,6 +55,7 @@ The scripts will take it from there, asking you for information and downloading
 - `install-stage1.sh`: sets up the base system and prepares for installation stage 2
 - `install-stage2.sh`: continues setting up things after booting into the freshly installed base system
 - `opt/grub-config`: the custom grub config generator to be installed in /opt/void-usb
+- `opt/backup-fs`: helper script to regenerate the squashfs
 - `procedure.txt`: notes to self, will disappear once finished
 - `bootup.sh`: script that sets up the overlay
 - `bashrc`: just a custom bashrc
diff --git a/install-stage1.sh b/install-stage1.sh
index e022984..2ac52f4 100644
--- a/install-stage1.sh
+++ b/install-stage1.sh
@@ -185,6 +185,14 @@ echo "%wheel ALL=(ALL:ALL) ALL" > /mnt/target/etc/sudoers.d/wheel_as_sudo_group.
 
 # TODO: add overlayfs scripts (bootup and shutdown)
 
+mkdir -p /mnt/target/opt/void-usb
+chmod 755 /mnt/target/opt/void-usb
+wget --output-document=/mnt/target/opt/void-usb/backup-fs https://lostcave.ddnss.de/git/BodgeMaster/void-minecraft-usb/raw/branch/master/opt/backup-fs
+chmod 744 /mnt/target/opt/void-usb/backup-fs
+
+echo "
+/opt/void-usb/backup-fs" >> /mnt/target/etc/rc.shutdown
+
 echo "# See fstab(5).
 # <device> <mount point> <fstype> <options> <dump> <pass>
 
@@ -280,8 +288,6 @@ run_in_target grub-install --target=i386-pc --boot-directory=/boot/efi/LOADER --
 run_in_target grub-install --target=i386-efi --boot-directory=/boot/efi/LOADER --efi-directory=/boot/efi --removable --no-nvram --modules="'$TARGET_PRELOAD_GRUB_MODULES'" "'/dev/$TARGET_DISK'"
 run_in_target grub-install --target=x86_64-efi --boot-directory=/boot/efi/LOADER --efi-directory=/boot/efi --removable --no-nvram --modules="'$TARGET_PRELOAD_GRUB_MODULES'" "'/dev/$TARGET_DISK'"
 
-mkdir -p /mnt/target/opt/void-usb
-chmod 755 /mnt/target/opt/void-usb
 wget --output-document=/mnt/target/opt/void-usb/grub-config https://lostcave.ddnss.de/git/BodgeMaster/void-minecraft-usb/raw/branch/master/opt/grub-config
 chmod 744 /mnt/target/opt/void-usb/grub-config
 
@@ -297,4 +303,6 @@ chmod 744 /mnt/target/etc/kernel.d/post-remove/99-void-usb
 
 run_in_target xbps-reconfigure -fa
 
+run_in_target /opt/void-usb/backup-fs
+
 #
diff --git a/opt/backup-fs b/opt/backup-fs
new file mode 100644
index 0000000..7e5face
--- /dev/null
+++ b/opt/backup-fs
@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+
+function yesno {
+  unset DISCARD_ME
+  while [ -z "$DISCARD_ME" ]; do
+    read -p "[y/n] " -n1 DISCARD_ME
+    case "$DISCARD_ME" in
+      y)
+        return 0
+        ;;
+      n)
+        return 1
+        ;;
+      *)
+        echo " Please enter y for yes or n for no."
+        unset DISCARD_ME
+        ;;
+    esac
+  done
+}
+
+# Overlay should still be mounted, right?
+
+cat /proc/mounts
+
+read -p "
+press any key" -n1 DISCARD_ME
+
+# And no services running?
+
+ps aux | grep -vF "[kworker"
+
+read -p "
+press any key" -n1 DISCARD_ME
+
+#TODO: remove above debugging sanity checks
+
+#TODO: refuse to run if system is running
+
+#TODO: add a way to tell the system whether to back up before shutting down
+
+#TODO: colors
+echo "Back up system changes to disk?
+
+This only affects things outside the /home directory.
+Backing up the system will take some time.
+"
+
+if yesno; then
+  echo "Backing up..."
+  #TODO: fiddle with squashfs parameters to find optimal settings
+  #TODO: What (if any) device nods need to be created? (man mksquashfs -> pseudo file)
+  mksquashfs / /container/new_squashfs.img -b 1M -comp xz -one-file-system -progress -noappend -e /var/cache/xbps
+  #TODO: check if enough disk space
+  # yes -> create new image next to old image
+  # no  -> create new image in RAM
+  #TODO: figure out when appending to existing squashfs is a good idea
+  mv /container/new_squashfs.img /container/squashfs.img
+else
+  echo ""
+  echo "Not backing up."
+fi