diff --git a/metropolis/installer/test/run_test.go b/metropolis/installer/test/run_test.go
index 925e758..3c8f1a6 100644
--- a/metropolis/installer/test/run_test.go
+++ b/metropolis/installer/test/run_test.go
@@ -124,7 +124,7 @@
 		return fmt.Errorf("couldn't read the installer ESP: %w", err)
 	}
 	// Make sure the EFI payload exists by attempting to open it.
-	efiPayload, err := fs.OpenFile(osimage.EFIPayloadPath, os.O_RDONLY)
+	efiPayload, err := fs.OpenFile("/"+osimage.EFIPayloadPath, os.O_RDONLY)
 	if err != nil {
 		return fmt.Errorf("couldn't open the installer's EFI Payload at %q: %w", osimage.EFIPayloadPath, err)
 	}