diff --git a/metropolis/installer/test/main.go b/metropolis/installer/test/main.go
index 82efb44..4bcf5d0 100644
--- a/metropolis/installer/test/main.go
+++ b/metropolis/installer/test/main.go
@@ -62,7 +62,7 @@
 		"-m", "512",
 		"-smp", "2",
 		"-cpu", "host",
-		"-drive", "if=pflash,format=raw,readonly,file=external/edk2/OVMF_CODE.fd",
+		"-drive", "if=pflash,format=raw,readonly=on,file=external/edk2/OVMF_CODE.fd",
 		"-drive", "if=pflash,format=raw,snapshot=on,file=external/edk2/OVMF_VARS.fd",
 		"-serial", "stdio",
 		"-no-reboot",