diff --git a/Makefile b/Makefile
index d7b4396..3f69e9a 100644
--- a/Makefile
+++ b/Makefile
@@ -47,8 +47,7 @@ ARCH = $(shell uname -m)
 BUILD_SERVER_CONTAINER=build-server
 # NUM_CPU is the number of CPUs available to Docker.  Used to control how many
 # test run in parallel
-NUM_CPU = $(shell docker info --format "{{ .NCPU }}")
-NUM_CPU ?= 2
+NUM_CPU = $(or $(shell docker info --format "{{ .NCPU }}"),2)
 # BASE_IMAGE_TAG is a normalized version of BASE_IMAGE, suitable for use in a Docker tag
 BASE_IMAGE_TAG=$(subst /,-,$(subst :,-,$(BASE_IMAGE)))
 MQ_IMAGE_DEVSERVER_BASE=mqadvanced-server-dev-base:$(MQ_VERSION)-$(ARCH)-$(BASE_IMAGE_TAG)