diff --git a/release/tools/vmimage.subr b/release/tools/vmimage.subr
index 84e718412d31..8eafceeb75f3 100644
--- a/release/tools/vmimage.subr
+++ b/release/tools/vmimage.subr
@@ -45,7 +45,7 @@ err() {
 }
 
 cleanup() {
-	if mount | grep -qE "devfs on ${DESTDIR}/dev"; then
+	if [ -c "${DESTDIR}/dev/null" ]; then
 		umount_loop ${DESTDIR}/dev 2>/dev/null
 	fi
 	umount_loop ${DESTDIR}