diff --git a/cmd/rebuild.go b/cmd/rebuild.go
index 6f235c3..ec56f72 100644
--- a/cmd/rebuild.go
+++ b/cmd/rebuild.go
@@ -15,7 +15,8 @@ import (
 var Rebuild wisski_distillery.Command = rebuild{}
 
 type rebuild struct {
-	Parallel    int `short:"p" long:"parallel" description:"run on (at most) this many instances in parallel. 0 for no limit." default:"1"`
+	Parallel    int    `short:"p" long:"parallel" description:"run on (at most) this many instances in parallel. 0 for no limit." default:"1"`
+	PHPVersion  string `short:"u" long:"php" description:"update to specific php version to use for instance. Should be one of '8.0', '8.1'."`
 	Positionals struct {
 		Slug []string `positional-arg-name:"SLUG" required:"0" description:"slug of instance or instances to run rebuild"`
 	} `positional-args:"true"`
@@ -49,6 +50,12 @@ func (rb rebuild) Run(context wisski_distillery.Context) (err error) {
 
 	// and do the actual rebuild
 	return status.WriterGroup(context.Stderr, rb.Parallel, func(instance *wisski.WissKI, writer io.Writer) error {
+		if rb.PHPVersion != "" {
+			if err := instance.Provisioner().ApplyFlags(context.Context, writer, rb.PHPVersion); err != nil {
+				return err
+			}
+		}
+
 		return instance.Barrel().Build(context.Context, writer, true)
 	}, wissKIs, status.SmartMessage(func(item *wisski.WissKI) string {
 		return fmt.Sprintf("rebuild %q", item.Slug)
diff --git a/internal/models/instances.go b/internal/models/instances.go
index aa103e6..36ed344 100644
--- a/internal/models/instances.go
+++ b/internal/models/instances.go
@@ -48,11 +48,13 @@ type Instance struct {
 	GraphDBPassword   string `gorm:"column:graphdb_password;not null"`
 }
 
+// TODO: Cleanup this stuff
 const (
-	PHP8         = "8.0"
-	PHP8_IMAGE   = "docker.io/library/php:8.0-apache-bullseye"
-	PHP8_1       = "8.1"
-	PHP8_1_IMAGE = "docker.io/library/php:8.1-apache-bullseye"
+	PHP_DEFAULT_IMAGE = PHP8_1
+	PHP8              = "8.0"
+	PHP8_IMAGE        = "docker.io/library/php:8.0-apache-bullseye"
+	PHP8_1            = "8.1"
+	PHP8_1_IMAGE      = "docker.io/library/php:8.1-apache-bullseye"
 )
 
 var errUnknownPHPVersion = errors.New("unknown php version")
@@ -61,7 +63,7 @@ var errUnknownPHPVersion = errors.New("unknown php version")
 func GetBaseImage(php string) (string, error) {
 	switch php {
 	case "":
-		return PHP8_IMAGE, nil
+		return PHP_DEFAULT_IMAGE, nil
 	case PHP8:
 		return PHP8_IMAGE, nil
 	case PHP8_1:
diff --git a/internal/wisski/ingredient/barrel/provisioner/provisioner.go b/internal/wisski/ingredient/barrel/provisioner/provisioner.go
index 592d6c5..f1ebb4b 100644
--- a/internal/wisski/ingredient/barrel/provisioner/provisioner.go
+++ b/internal/wisski/ingredient/barrel/provisioner/provisioner.go
@@ -6,8 +6,10 @@ import (
 	"io"
 	"strings"
 
+	"github.com/FAU-CDI/wisski-distillery/internal/models"
 	"github.com/FAU-CDI/wisski-distillery/internal/wisski/ingredient"
 	"github.com/FAU-CDI/wisski-distillery/internal/wisski/ingredient/barrel"
+	"github.com/FAU-CDI/wisski-distillery/internal/wisski/ingredient/bookkeeping"
 	"github.com/alessio/shellescape"
 	"github.com/tkw1536/pkglib/stream"
 )
@@ -18,10 +20,27 @@ import (
 type Provisioner struct {
 	ingredient.Base
 	Dependencies struct {
-		Barrel *barrel.Barrel
+		Barrel      *barrel.Barrel
+		Bookkeeping *bookkeeping.Bookkeeping
 	}
 }
 
+// ApplyFlags applies flags to an already provisioned instance.
+func (provision *Provisioner) ApplyFlags(ctx context.Context, progress io.Writer, phpversion string) (err error) {
+	// setup the new docker image
+	provision.Instance.DockerBaseImage, err = models.GetBaseImage(phpversion)
+	if err != nil {
+		return err
+	}
+
+	// save in bookkeeping
+	if err := provision.Dependencies.Bookkeeping.Save(ctx); err != nil {
+		return err
+	}
+
+	return provision.Dependencies.Barrel.Build(ctx, progress, true)
+}
+
 // Provision provisions an instance, assuming that the required databases already exist.
 func (provision *Provisioner) Provision(ctx context.Context, progress io.Writer) error {