diff --git a/metropolis/test/installer/main.go b/metropolis/test/installer/main.go
index 0f2f40e..a5bac64 100644
--- a/metropolis/test/installer/main.go
+++ b/metropolis/test/installer/main.go
@@ -180,19 +180,19 @@
 	// generated by Metropolis buildsystem.
 	installer, err := os.Open(installerEFIPayload)
 	if err != nil {
-		log.Fatalf("Couldn't open the installer EFI executable at %q: %s", installerEFIPayload, err.Error())
+		log.Fatalf("Couldn't open the installer EFI executable at %q: %v", installerEFIPayload, err)
 	}
 	info, err := installer.Stat()
 	if err != nil {
-		log.Fatalf("Couldn't stat the installer EFI executable: %s", err.Error())
+		log.Fatalf("Couldn't stat the installer EFI executable: %v", err)
 	}
 	bundle, err := os.Open(testOSBundle)
 	if err != nil {
-		log.Fatalf("failed to open TestOS bundle: %v", err)
+		log.Fatalf("Failed to open TestOS bundle: %v", err)
 	}
 	bundleStat, err := bundle.Stat()
 	if err != nil {
-		log.Fatalf("failed to stat() TestOS bundle: %v", err)
+		log.Fatalf("Failed to stat() TestOS bundle: %v", err)
 	}
 	iargs := mctl.MakeInstallerImageArgs{
 		Installer:     installer,
@@ -203,7 +203,7 @@
 		BundleSize:    uint64(bundleStat.Size()),
 	}
 	if err := mctl.MakeInstallerImage(iargs); err != nil {
-		log.Fatalf("Couldn't create the installer image at %q: %s", installerImage, err.Error())
+		log.Fatalf("Couldn't create the installer image at %q: %v", installerImage, err)
 	}
 	// With common dependencies set up, run the tests.
 	code := m.Run()