diff --git a/scripts/runqemu b/scripts/runqemu
index 90998aeab4..290f9ccce5 100755
--- a/scripts/runqemu
+++ b/scripts/runqemu
@@ -54,9 +54,9 @@ error() {
 }
 
 MACHINE=${MACHINE:=""}
-KERNEL=""
+KERNEL=${KERNEL:=""}
+ROOTFS=${ROOTFS:=""}
 FSTYPE=""
-ROOTFS=""
 LAZY_ROOTFS=""
 SCRIPT_QEMU_OPT=""
 SCRIPT_QEMU_EXTRA_OPT=""