diff --git a/cros_workon b/cros_workon
index 374f15d0e8..1a9626b1f6 100755
--- a/cros_workon
+++ b/cros_workon
@@ -61,20 +61,28 @@ else
   EBUILDCMD=ebuild
 fi
 
+WORKON_DIR=${CHROOT_TRUNK_DIR}/.config/cros_workon
 KEYWORDS_DIR=${BOARD_DIR}/etc/portage/package.keywords
 UNMASK_DIR=${BOARD_DIR}/etc/portage/package.unmask
+WORKON_FILE=${WORKON_DIR}/${FLAGS_board:-host}
 KEYWORDS_FILE=${KEYWORDS_DIR}/cros-workon
 UNMASK_FILE=${UNMASK_DIR}/cros-workon
 
-sudo mkdir -p "${KEYWORDS_DIR}" "${UNMASK_DIR}" || \
-  die "mkdir -p ${KEYWORDS_DIR} ${UNMASK_DIR}"
+# TODO(msb): remove the backward compatibility after 09/01/2010
+sudo mkdir -p "${WORKON_DIR}" "${KEYWORDS_DIR}" "${UNMASK_DIR}" || \
+  die "mkdir -p ${WORKON_DIR} ${KEYWORDS_DIR} ${UNMASK_DIR}"
 if [ ! -L "${KEYWORDS_FILE}" ]; then
   sudo rm -f "${KEYWORDS_FILE}"
-  sudo ln -s "${UNMASK_FILE}" "${KEYWORDS_FILE}" || \
-    die "ln -s ${UNMASK_FILE} ${KEYWORDS_FILE}"
+  sudo ln -s "${WORKON_FILE}" "${KEYWORDS_FILE}" || \
+    die "ln -s ${WORKON_FILE} ${KEYWORDS_FILE}"
 fi
-sudo touch "${UNMASK_FILE}" || \
-  die "touch ${UNMASK_FILE}"
+if [ ! -L "${UNMASK_FILE}" ]; then
+  [ -f "${UNMASK_FILE}" ] && sudo mv "${UNMASK_FILE}" "${WORKON_FILE}"
+  sudo ln -s "${WORKON_FILE}" "${UNMASK_FILE}" || \
+    die "ln -s ${WORKON_FILE} ${UNMASK_FILE}"
+fi
+sudo touch "${WORKON_FILE}" || \
+  die "touch ${WORKON_FILE}"
 
 # Canonicalize package name to category/package.
 canonicalize_name () {
@@ -113,7 +121,7 @@ canonicalize_names () {
 
 # Display ebuilds currently part of the live branch and open for development.
 show_live_ebuilds () {
-  sed -n 's/^[~=]\(.*\)-9999$/\1/p' "${UNMASK_FILE}"
+  sed -n 's/^[~=]\(.*\)-9999$/\1/p' "${WORKON_FILE}"
 }
 
 find_repo_dir () {
@@ -171,8 +179,8 @@ ebuild_to_live () {
   local atoms=$1
 
   for atom in ${atoms}; do
-    if ! grep -qx "[~=]${atom}-9999" "${UNMASK_FILE}" ; then
-      sudo bash -c "echo \"=${atom}-9999\" >> \"${UNMASK_FILE}\""
+    if ! grep -qx "[~=]${atom}-9999" "${WORKON_FILE}" ; then
+      sudo bash -c "echo \"=${atom}-9999\" >> \"${WORKON_FILE}\""
     else
       warn "Already working on ${atom}"
     fi
@@ -184,10 +192,10 @@ ebuild_to_stable () {
   local atoms=$1
 
   for atom in ${atoms}; do
-    if grep -qx "[~=]${atom}-9999" "${UNMASK_FILE}" ; then
-      sudo bash -c "grep -v '^[~=]${atom}-9999\$' \"${UNMASK_FILE}\" > \
-          \"${UNMASK_FILE}+\""
-      sudo mv "${UNMASK_FILE}+" "${UNMASK_FILE}"
+    if grep -qx "[~=]${atom}-9999" "${WORKON_FILE}" ; then
+      sudo bash -c "grep -v '^[~=]${atom}-9999\$' \"${WORKON_FILE}\" > \
+          \"${WORKON_FILE}+\""
+      sudo mv "${WORKON_FILE}+" "${WORKON_FILE}"
     else
       warn "Not working on ${atom}"
     fi