diff --git a/Makefile b/Makefile
index 408d6a4..bd091d5 100644
--- a/Makefile
+++ b/Makefile
@@ -57,7 +57,7 @@ _ck_root:
 	[ `whoami` = 'root' ] # Only root can summon vmdb2 ☹
 
 _clean_yaml:
-	rm -f $(addsuffix .yaml,$(platforms)) raspi_base_buster.yaml raspi_base_bullseye.yaml
+	rm -f $(addsuffix .yaml,$(platforms)) raspi_base_buster.yaml raspi_base_bullseye.yaml raspi_base_bookworm.yaml
 _clean_images:
 	rm -f $(addsuffix .img,$(platforms))
 _clean_xzimages:
diff --git a/raspi_master.yaml b/raspi_master.yaml
index bfae52a..683f71e 100644
--- a/raspi_master.yaml
+++ b/raspi_master.yaml
@@ -134,14 +134,17 @@ steps:
       rm -rf /var/lib/apt/lists
 
   # Modify the kernel commandline we take from the firmware to boot from
-  # the partition labeled raspiroot instead of forcing it to mmcblk0p2
+  # the partition labeled raspiroot instead of forcing it to mmcblk0p2.
+  # Also insert the serial console right before the root= parameter.
   #
   # These changes will be overwritten after the hardware is probed
-  # after dpkg reconfigures raspi-firmware (upon first boot).
+  # after dpkg reconfigures raspi-firmware (upon first boot), so make
+  # sure we don't lose label-based booting.
   - chroot: /
     shell: |
-      sed -i 's/^/console=__SERIAL_CONSOLE__ /' /boot/firmware/cmdline.txt
-      sed -i 's/.dev.mmcblk0p2/LABEL=RASPIROOT/' /boot/firmware/cmdline.txt
+      sed -i 's/root=/console=__SERIAL_CONSOLE__ root=/' /boot/firmware/cmdline.txt
+      sed -i 's#root=/dev/mmcblk0p2#root=LABEL=RASPIROOT#' /boot/firmware/cmdline.txt
+      sed -i 's/^#ROOTPART=.*/ROOTPART=LABEL=RASPIROOT/' /etc/default/raspi-firmware
 
       __EXTRA_CHROOT_SHELL_CMDS__
 
@@ -160,6 +163,8 @@ steps:
   #   populated during installation.
   #
   # Note this will also trigger ConditionFirstBoot=yes for systemd.
+  # On Buster, /etc/machine-id should be an emtpy file, not an absent file
+  # On Bullseye, /etc/machine-id should not exist in an image
   - chroot: /
     shell: |
       rm -f /etc/machine-id /var/lib/dbus/machine-id