diff --git a/stackrc b/stackrc
index 3dc800a..ebe472c 100755
--- a/stackrc
+++ b/stackrc
@@ -623,7 +623,8 @@
 case "$VIRT_DRIVER" in
     ironic|libvirt)
         LIBVIRT_TYPE=${LIBVIRT_TYPE:-kvm}
-        LIBVIRT_CPU_MODE=${LIBVIRT_CPU_MODE:-none}
+        LIBVIRT_CPU_MODE=${LIBVIRT_CPU_MODE:-custom}
+        LIBVIRT_CPU_MODEL=${LIBVIRT_CPU_MODEL:-Nehalem}
         if [[ "$os_VENDOR" =~ (Debian|Ubuntu) ]]; then
             # The groups change with newer libvirt. Older Ubuntu used
             # 'libvirtd', but now uses libvirt like Debian. Do a quick check