diff --git a/image_common.sh b/lib/cros_image_common.sh
similarity index 100%
rename from image_common.sh
rename to lib/cros_image_common.sh
diff --git a/make_factory_package.sh b/make_factory_package.sh
index a251980a12..a62cfe2e3c 100755
--- a/make_factory_package.sh
+++ b/make_factory_package.sh
@@ -19,7 +19,8 @@
 . "$(dirname "$0")/chromeos-common.sh"
 
 # Load functions designed for image processing
-. "$(dirname "$0")/image_common.sh"
+. "$(dirname "$0")/lib/cros_image_common.sh" ||
+  die "Cannot load required library: lib/cros_image_common.sh; Abort."
 
 get_default_board
 
diff --git a/mk_memento_images.sh b/mk_memento_images.sh
index b5d786135c..415768fb4b 100755
--- a/mk_memento_images.sh
+++ b/mk_memento_images.sh
@@ -10,13 +10,13 @@
 
 set -e
 
-LIB_IMAGE_COMMON="$(dirname "$0")/image_common.sh"
-if ! . "$LIB_IMAGE_COMMON"; then
-  echo "Missing required library: $LIB_IMAGE_COMMON. Cannot continue."
+# Load functions designed for image processing
+if ! . "$(dirname "$0")/lib/cros_image_common.sh"; then
+  echo "ERROR: Cannot load required library: lib/cros_image_common.sh; Abort."
   exit 1
 fi
 
-if [ -z "$2" -o -z "$1" ]; then
+if [ -z "$2" -o -z "$1" ] || [ "${#@}" -ne 2 -a "${#@}" -ne 3 ]; then
   echo "usage: $0 path/to/kernel_partition_img path/to/rootfs_partition_img"
   echo "    or $0 path/to/chromiumos_img kern_part_no rootfs_part_no"
   exit 1