diff --git a/build_image b/build_image
index 1d3d3c9195..409818dcce 100755
--- a/build_image
+++ b/build_image
@@ -1,3 +1,4 @@
+#!/bin/bash
 
 # Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
@@ -8,42 +9,10 @@
 # the given target's root with binary packages turned on. This script will
 # build the Chrome OS image using only pre-built binary packages.
 
-# Load common CrOS utilities.  Inside the chroot this file is installed in
-# /usr/lib/crosutils.  Outside the chroot we find it relative to the script's
-# location.
-find_common_sh() {
-  local common_paths=(/usr/lib/crosutils $(dirname "$0"))
-  local path
+SCRIPT_ROOT=$(dirname "$0")
+. "${SCRIPT_ROOT}/build_library/build_common.sh" || exit 1
 
-  SCRIPT_ROOT=
-  for path in "${common_paths[@]}"; do
-    local common="${path}/common.sh"
-    if ([ -r "${common}" ] && . "${common}" && [ -d "${SCRIPTS_DIR}" ]); then
-      SCRIPT_ROOT=${path}
-      break
-    fi
-  done
-}
 
-find_common_sh
-. "${SCRIPT_ROOT}/common.sh" || ! echo "Unable to load common.sh" || exit 1
-
-# Load functions and constants for chromeos-install
-[ -f /usr/lib/installer/chromeos-common.sh ] && \
-  INSTALLER_ROOT=/usr/lib/installer || \
-  INSTALLER_ROOT=$(dirname "$(readlink -f "$0")")
-
-. "${INSTALLER_ROOT}/chromeos-common.sh" || \
-  die "Unable to load chromeos-common.sh"
-
-locate_gpt
-
-# Script must be run inside the chroot.
-restart_in_chroot_if_needed "$@"
-
-get_default_board
-
-# Flags.
 DEFINE_string board "${DEFAULT_BOARD}" \
   "The board to build an image for."
 DEFINE_string build_root "/build" \
diff --git a/build_library/build_common.sh b/build_library/build_common.sh
new file mode 100644
index 0000000000..a77f736b32
--- /dev/null
+++ b/build_library/build_common.sh
@@ -0,0 +1,21 @@
+# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+# Common library file to be sourced by build_image,
+# mod_image_for_test.sh, and mod_image_for_recovery.sh.  This
+# file ensures that library source files needed by all the scripts
+# are included once, and also takes care of certain bookeeping tasks
+# common to all the scripts.
+
+# SCRIPT_ROOT must be set prior to sourcing this file
+. "${SCRIPT_ROOT}/common.sh" || exit 1
+
+# All scripts using this file must be run inside the chroot.
+restart_in_chroot_if_needed "$@"
+
+INSTALLER_ROOT=/usr/lib/installer
+. "${INSTALLER_ROOT}/chromeos-common.sh" || exit 1
+
+locate_gpt
+get_default_board
diff --git a/mod_image_for_recovery.sh b/mod_image_for_recovery.sh
index 93c3239585..485fa11b38 100755
--- a/mod_image_for_recovery.sh
+++ b/mod_image_for_recovery.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-# Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
@@ -9,37 +9,9 @@
 # kernel.  Alternatively, a signed recovery kernel can be used to
 # create a Chromium OS recovery image.
 
-# --- BEGIN COMMON.SH BOILERPLATE ---
-# Load common CrOS utilities.  Inside the chroot this file is installed in
-# /usr/lib/crosutils.  Outside the chroot we find it relative to the script's
-# location.
-find_common_sh() {
-  local common_paths=(/usr/lib/crosutils $(dirname "$(readlink -f "$0")"))
-  local path
+SCRIPT_ROOT=$(dirname "$0")
+. "${SCRIPT_ROOT}/build_library/build_common.sh" || exit 1
 
-  SCRIPT_ROOT=
-  for path in "${common_paths[@]}"; do
-    if [ -r "${path}/common.sh" ]; then
-      SCRIPT_ROOT=${path}
-      break
-    fi
-  done
-}
-
-find_common_sh
-. "${SCRIPT_ROOT}/common.sh" || { echo "Unable to load common.sh"; exit 1; }
-# --- END COMMON.SH BOILERPLATE ---
-
-# Need to be inside the chroot to load chromeos-common.sh
-assert_inside_chroot
-
-# Load functions and constants for chromeos-install
-. "/usr/lib/installer/chromeos-common.sh" || \
-  die "Unable to load /usr/lib/installer/chromeos-common.sh"
-
-locate_gpt
-
-get_default_board
 
 DEFINE_string board "$DEFAULT_BOARD" "Board for which the image was built" b
 DEFINE_integer statefulfs_sectors 4096 \
diff --git a/mod_image_for_test.sh b/mod_image_for_test.sh
index 8ba2e3f1ee..48793c6f59 100755
--- a/mod_image_for_test.sh
+++ b/mod_image_for_test.sh
@@ -19,35 +19,9 @@
 # TODO(vlaviano): delete this script.
 # =============================================================================
 
-# --- BEGIN COMMON.SH BOILERPLATE ---
-# Load common CrOS utilities.  Inside the chroot this file is installed in
-# /usr/lib/crosutils.  Outside the chroot we find it relative to the script's
-# location.
-find_common_sh() {
-  local common_paths=(/usr/lib/crosutils $(dirname "$(readlink -f "$0")"))
-  local path
+SCRIPT_ROOT=$(dirname "$0")
+. "${SCRIPT_ROOT}/build_library/build_common.sh" || exit 1
 
-  SCRIPT_ROOT=
-  for path in "${common_paths[@]}"; do
-    if [ -r "${path}/common.sh" ]; then
-      SCRIPT_ROOT=${path}
-      break
-    fi
-  done
-}
-
-find_common_sh
-. "${SCRIPT_ROOT}/common.sh" || { echo "Unable to load common.sh"; exit 1; }
-# --- END COMMON.SH BOILERPLATE ---
-
-# Need to be inside the chroot to load chromeos-common.sh
-assert_inside_chroot
-
-# Load functions and constants for chromeos-install
-. "/usr/lib/installer/chromeos-common.sh" || \
-  die "Unable to load /usr/lib/installer/chromeos-common.sh"
-
-get_default_board
 
 DEFINE_string board "$DEFAULT_BOARD" "Board for which the image was built" b
 DEFINE_boolean factory $FLAGS_FALSE \