diff --git a/build.sh b/build.sh
index 986f81c..ca0fb57 100755
--- a/build.sh
+++ b/build.sh
@@ -226,7 +226,7 @@ export TARGET_HOSTNAME=${TARGET_HOSTNAME:-raspberrypi}
 export FIRST_USER_NAME=${FIRST_USER_NAME:-pi}
 export FIRST_USER_PASS
 export DISABLE_FIRST_BOOT_USER_RENAME=${DISABLE_FIRST_BOOT_USER_RENAME:-0}
-export RELEASE=${RELEASE:-bullseye} # Don't forget to update stage0/prerun.sh
+export RELEASE=${RELEASE:-bookworm} # Don't forget to update stage0/prerun.sh
 export WPA_ESSID
 export WPA_PASSWORD
 export WPA_COUNTRY
diff --git a/stage0/prerun.sh b/stage0/prerun.sh
index 024d369..c8e51a4 100755
--- a/stage0/prerun.sh
+++ b/stage0/prerun.sh
@@ -1,6 +1,6 @@
 #!/bin/bash -e
 
-if [ "$RELEASE" != "bullseye" ]; then
+if [ "$RELEASE" != "bookworm" ]; then
 	echo "WARNING: RELEASE does not match the intended option for this branch."
 	echo "         Please check the relevant README.md section."
 fi