deleted file mode 100644
--- a/mail/themes/Makefile.in
+++ /dev/null
@@ -1,5 +0,0 @@
-# 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/.
-
-DIST_FILES = install.rdf

--- a/mail/themes/moz.build
+++ b/mail/themes/moz.build
@@ -9,8 +9,12 @@ elif CONFIG['MOZ_WIDGET_TOOLKIT'] == 'co
     DIRS += ['osx']
 else:
     DIRS += ['windows']
 
 classic_extension_dir = '{972ce4c6-7e08-4474-a285-3208198ce6fd}'
 
 DEFINES['THUNDERBIRD_VERSION'] = CONFIG['THUNDERBIRD_VERSION']
 DIST_SUBDIR = 'extensions/' + classic_extension_dir
+
+FINAL_TARGET_PP_FILES += [
+    'install.rdf',
+]