diff --git a/tools/boot/ci-qemu-test.sh b/tools/boot/ci-qemu-test.sh
index b730e972501..9548c6a1289 100755
--- a/tools/boot/ci-qemu-test.sh
+++ b/tools/boot/ci-qemu-test.sh
@@ -85,7 +85,7 @@ amd64)
 	if [ ! -r "${OVMF}" ]; then
 		die "Cannot read UEFI firmware file ${OVMF}"
 	fi
-	QEMU="qemu-system-x86_64 -drive if=pflash,format=raw,readonly,file=${OVMF}"
+	QEMU="qemu-system-x86_64 -drive if=pflash,format=raw,readonly=on,file=${OVMF}"
 	EFIBOOT=BOOTx64.EFI
 	ROOTDEV=ada0s1
 	;;