diff --git a/metropolis/installer/test/BUILD.bazel b/metropolis/installer/test/BUILD.bazel
index 7f7ad54..7b7828d 100644
--- a/metropolis/installer/test/BUILD.bazel
+++ b/metropolis/installer/test/BUILD.bazel
@@ -24,6 +24,7 @@
         "//metropolis/proto/api",
         "//osbase/build/mkimage/osimage",
         "//osbase/cmd",
+        "//osbase/structfs",
         "@com_github_diskfs_go_diskfs//:go-diskfs",
         "@com_github_diskfs_go_diskfs//disk",
         "@com_github_diskfs_go_diskfs//partition/gpt",
diff --git a/metropolis/installer/test/run_test.go b/metropolis/installer/test/run_test.go
index 766c839..cd87852 100644
--- a/metropolis/installer/test/run_test.go
+++ b/metropolis/installer/test/run_test.go
@@ -7,7 +7,6 @@
 package installer
 
 import (
-	"bytes"
 	"context"
 	"fmt"
 	"log"
@@ -27,6 +26,7 @@
 	mctl "source.monogon.dev/metropolis/cli/metroctl/core"
 	"source.monogon.dev/osbase/build/mkimage/osimage"
 	"source.monogon.dev/osbase/cmd"
+	"source.monogon.dev/osbase/structfs"
 )
 
 var (
@@ -134,21 +134,21 @@
 func TestMain(m *testing.M) {
 	installerImage = filepath.Join(os.Getenv("TEST_TMPDIR"), "installer.img")
 
-	installer, err := os.ReadFile(xInstallerPath)
+	installer, err := structfs.OSPathBlob(xInstallerPath)
 	if err != nil {
 		log.Fatal(err)
 	}
 
-	bundle, err := os.ReadFile(xBundlePath)
+	bundle, err := structfs.OSPathBlob(xBundlePath)
 	if err != nil {
 		log.Fatal(err)
 	}
 
 	iargs := mctl.MakeInstallerImageArgs{
-		Installer:  bytes.NewReader(installer),
+		Installer:  installer,
 		TargetPath: installerImage,
 		NodeParams: &api.NodeParameters{},
-		Bundle:     bytes.NewReader(bundle),
+		Bundle:     bundle,
 	}
 	if err := mctl.MakeInstallerImage(iargs); err != nil {
 		log.Fatalf("Couldn't create the installer image at %q: %v", installerImage, err)