diff --git a/build_image b/build_image
index 32fcccc377..581186edc3 100755
--- a/build_image
+++ b/build_image
@@ -282,8 +282,9 @@ fi
 
 print_time_elapsed
 
-echo "To copy to USB keyfob, do something like:"
-echo "  ./image_to_usb.sh --from=${OUTSIDE_OUTPUT_DIR} --to=/dev/sdX"
-echo "To convert to VMWare image, INSIDE the chroot, do something like:"
-echo "  ./image_to_vm.sh --from=${OUTSIDE_OUTPUT_DIR} --board=${BOARD}"
-echo "from the scripts directory where you entered the chroot."
+cat << EOF
+To copy the image to a USB key, use:
+  ./image_to_usb.sh --from=${OUTSIDE_OUTPUT_DIR}
+To convert it to a VMWare image, use:
+  ./image_to_vm.sh --from=${OUTSIDE_OUTPUT_DIR} --board=${BOARD}
+EOF
diff --git a/image_to_usb.sh b/image_to_usb.sh
index fba9510bec..7d61545744 100755
--- a/image_to_usb.sh
+++ b/image_to_usb.sh
@@ -145,6 +145,15 @@ if [ ! -d "${FLAGS_from}" ] ; then
   die_notrace "Cannot find image directory ${FLAGS_from}"
 fi
 
+# TODO(garnold) This code reinstates the previous default value for --to, which
+# some users relied upon to trigger target device auto-detection. It should be
+# removed once we're sure that all users have adapted to simply not specifying
+# --to. The instructions emitted by build_image were changed accordingly.
+if [ "${FLAGS_to}" == "/dev/sdX" ]; then
+  warn "the use of --to=/dev/sdX is deprecated, just omit --to instead"
+  FLAGS_to=""
+fi
+
 # No target provided, attempt autodetection.
 if [ -z "${FLAGS_to}" ]; then
   if [ ${FLAGS_yes} -eq ${FLAGS_TRUE} ]; then