--- a/mail/confvars.sh
+++ b/mail/confvars.sh
@@ -8,19 +8,16 @@ MOZ_APP_NAME=thunderbird
 MOZ_UPDATER=1
 
 if test "$OS_ARCH" = "WINNT"; then
   if ! test "$HAVE_64BIT_BUILD"; then
     MOZ_VERIFY_MAR_SIGNATURE=1
   fi
 fi
 
-MOZ_APP_VERSION=$THUNDERBIRD_VERSION
-MOZ_APP_VERSION_DISPLAY=$THUNDERBIRD_VERSION_DISPLAY
-
 BROWSER_CHROME_URL=chrome://messenger/content/messengercompose/messengercompose.xul
 
 MOZ_BRANDING_DIRECTORY=$commreltopsrcdir/mail/branding/nightly
 MOZ_OFFICIAL_BRANDING_DIRECTORY=$commreltopsrcdir/mail/branding/thunderbird
 
 MOZ_APP_ID={3550f703-e582-4d05-9a08-453d09bdfdc6}
 # This should usually be the same as the value MAR_CHANNEL_ID.
 # If more than one ID is needed, then you should use a comma separated list

--- a/mail/installer/windows/moz.build
+++ b/mail/installer/windows/moz.build
@@ -1,10 +1,12 @@
 # vim: set filetype=python:
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+DEFINES['APP_VERSION'] = CONFIG['MOZ_APP_VERSION']
+
 DEFINES['MOZ_APP_NAME'] = CONFIG['MOZ_APP_NAME']
 DEFINES['MOZ_APP_DISPLAYNAME'] = CONFIG['MOZ_APP_DISPLAYNAME']
 DEFINES['MOZILLA_VERSION'] = CONFIG['MOZILLA_VERSION']
 DEFINES['MOZ_APP_VERSION'] = CONFIG['MOZ_APP_VERSION']
 DEFINES['PRE_RELEASE_SUFFIX'] = ''