diff --git a/build_image b/build_image
index a9f54ecf99..5ea08da4b2 100755
--- a/build_image
+++ b/build_image
@@ -12,6 +12,11 @@
 SCRIPT_ROOT=$(dirname $(readlink -f "$0"))
 . "${SCRIPT_ROOT}/common.sh" || exit 1
 
+# Script must run inside the chroot
+restart_in_chroot_if_needed "$@"
+
+assert_not_root_user
+
 # Developer-visible flags.
 DEFINE_string board "${DEFAULT_BOARD}" \
   "The board to build an image for."
diff --git a/build_library/vm_image_util.sh b/build_library/vm_image_util.sh
index 2b41b36262..163fa424b9 100644
--- a/build_library/vm_image_util.sh
+++ b/build_library/vm_image_util.sh
@@ -11,6 +11,7 @@ VALID_IMG_TYPES=(
     openstack
     qemu
     rackspace
+    rackspace_vhd
     vagrant
     vagrant_vmware_fusion
     virtualbox
@@ -66,6 +67,7 @@ IMG_qemu_CONF_FORMAT=qemu
 
 ## xen
 IMG_xen_BOOT_KERNEL=0
+IMG_xen_DISK_FORMAT=vhd
 IMG_xen_CONF_FORMAT=xl
 
 ## virtualbox
@@ -118,6 +120,9 @@ IMG_gce_OEM_PACKAGE=oem-gce
 ## rackspace
 IMG_rackspace_BOOT_KERNEL=0
 IMG_rackspace_OEM_PACKAGE=oem-rackspace
+IMG_rackspace_vhd_BOOT_KERNEL=0
+IMG_rackspace_vhd_DISK_FORMAT=vhd
+IMG_rackspace_vhd_OEM_PACKAGE=oem-rackspace
 
 ###########################################################
 
@@ -256,6 +261,10 @@ _write_qcow2_disk() {
     qemu-img convert -f raw "$1" -O qcow2 "$2"
 }
 
+_write_vhd_disk() {
+    qemu-img convert -f raw "$1" -O vpc "$2"
+}
+
 _write_vmdk_ide_disk() {
     qemu-img convert -f raw "$1" -O vmdk -o adapter_type=ide "$2"
 }
@@ -449,6 +458,7 @@ _write_xl_conf() {
     local dst_dir=$(dirname "$VM_DST_IMG")
     local pygrub="${dst_dir}/$(_src_to_dst_name "${src_name}" "_pygrub.cfg")"
     local pvgrub="${dst_dir}/$(_src_to_dst_name "${src_name}" "_pvgrub.cfg")"
+    local disk_format=$(_get_vm_opt DISK_FORMAT)
 
     # Set up the few differences between pygrub and pvgrub
     echo '# Xen PV config using pygrub' > "${pygrub}"
@@ -469,7 +479,7 @@ memory = "${vm_mem}"
 vcpus = 2
 # TODO(marineam): networking...
 vif = [ ]
-disk = [ '${dst_name},raw,xvda' ]
+disk = [ '${dst_name},${disk_format},xvda' ]
 EOF
 
     cat > "${VM_README}" <<EOF
diff --git a/image_to_vm.sh b/image_to_vm.sh
index 37d25de020..585f02abe4 100755
--- a/image_to_vm.sh
+++ b/image_to_vm.sh
@@ -8,10 +8,15 @@
 # disk image, supporting a variety of different targets.
 
 
-
 # Helper scripts should be run from the same location as this script.
 SCRIPT_ROOT=$(dirname "$(readlink -f "$0")")
 . "${SCRIPT_ROOT}/common.sh" || exit 1
+
+# Script must run inside the chroot
+restart_in_chroot_if_needed "$@"
+
+assert_not_root_user
+
 . "${BUILD_LIBRARY_DIR}/toolchain_util.sh" || exit 1
 . "${BUILD_LIBRARY_DIR}/build_image_util.sh" || exit 1
 . "${BUILD_LIBRARY_DIR}/vm_image_util.sh" || exit 1