diff --git a/release/Makefile.vm b/release/Makefile.vm
index 71a4392b6b0..8c48c0a13dc 100644
--- a/release/Makefile.vm
+++ b/release/Makefile.vm
@@ -25,31 +25,31 @@ CLOUDWARE_TYPES?= AZURE \
 		OCI \
 		VAGRANT
 AZURE_FORMAT=	vhdf
-AZURE_FSLIST=	ufs zfs
+AZURE_FSLIST?=	ufs zfs
 AZURE_DESC=	Microsoft Azure platform image
 BASIC-CI_FORMAT=	raw
-BASIC-CI_FSLIST=	ufs
+BASIC-CI_FSLIST?=	ufs
 BASIC-CI_DESC=		Image for CI
 BASIC-CLOUDINIT_FORMAT=	raw qcow2
 BASIC-CLOUDINIT_FSLIST?=	ufs zfs
 BASIC-CLOUDINIT_DESC?=	Images for VM with cloudinit disk config support
 EC2_FORMAT=	raw
-EC2_FSLIST=	ufs zfs
-EC2_FLAVOURS=	BASE CLOUD-INIT
+EC2_FSLIST?=	ufs zfs
+EC2_FLAVOURS?=	BASE CLOUD-INIT
 EC2-BASE_DESC=	Amazon EC2 image
 EC2-CLOUD-INIT_DESC=	Amazon EC2 Cloud-Init image
 GCE_FORMAT=	raw
-GCE_FSLIST=	ufs zfs
+GCE_FSLIST?=	ufs zfs
 GCE_DESC=	Google Compute Engine image
 OCI_FORMAT=	qcow2
-OCI_FSLIST=	ufs
+OCI_FSLIST?=	ufs
 OCI_DESC=	Oracle Cloud Infrastructure image
 OPENSTACK_FORMAT=qcow2
-OPENSTACK_FSLIST=	ufs
+OPENSTACK_FSLIST?=	ufs
 OPENSTACK_DESC=	OpenStack platform image
 VAGRANT_FORMAT=	vmdk
-VAGRANT_FSLIST=	ufs
-VAGRANT_FLAVOURS=	VIRTUALBOX VMWARE
+VAGRANT_FSLIST?=	ufs
+VAGRANT_FLAVOURS?=	VIRTUALBOX VMWARE
 VAGRANT-VIRTUALBOX_DESC=	Vagrant Image for VirtualBox
 VAGRANT-VMWARE_DESC=	Vagrant Image for VMWare