diff --git a/examples/make-deploy/virtualbox.makefile b/examples/make-deploy/virtualbox.makefile
index f21070a4..66f93dec 100644
--- a/examples/make-deploy/virtualbox.makefile
+++ b/examples/make-deploy/virtualbox.makefile
@@ -1,7 +1,7 @@
 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-virtualbox-vm: VIRTUALBOX_CPUS?=4
+virtualbox-vm: VIRTUALBOX_CPU_COUNT?=4
 virtualbox-vm: VIRTUALBOX_DISK_SIZE?=100000
 virtualbox-vm: VIRTUALBOX_MEMORY_SIZE?=4096
 virtualbox-vm: check