--- a/calendar/base/Makefile.in
+++ b/calendar/base/Makefile.in
@@ -5,18 +5,16 @@
 
 DEPTH		= @DEPTH@
 topsrcdir	= @top_srcdir@
 srcdir		= @srcdir@
 VPATH		= @srcdir@
 
 include $(DEPTH)/config/autoconf.mk
 
-USE_EXTENSION_MANIFEST = 1
-
 WINDOW_ICONS = calendar-alarm-dialog \
                calendar-event-dialog \
                calendar-event-summary-dialog \
                calendar-task-dialog \
                calendar-task-summary-dialog \
                $(NULL)
 
 include $(topsrcdir)/config/rules.mk

--- a/calendar/import-export/Makefile.in
+++ b/calendar/import-export/Makefile.in
@@ -4,17 +4,16 @@
 
 DEPTH   = @DEPTH@
 topsrcdir = @top_srcdir@
 srcdir    = @srcdir@
 VPATH   = @srcdir@
 
 include $(DEPTH)/config/autoconf.mk
 
-USE_EXTENSION_MANIFEST = 1
 EXTRA_SCRIPTS = \
     calHtmlExport.js \
     calIcsImportExport.js \
     calListFormatter.js \
     calMonthGridPrinter.js \
     calOutlookCSVImportExport.js \
     calWeekPrinter.js \
     $(NULL)

--- a/calendar/lightning/Makefile.in
+++ b/calendar/lightning/Makefile.in
@@ -1,16 +1,15 @@
 # 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/.
 
 # Calendar builders currently use STRIP_XPI to reduce the binary component in
 # Lightning.
 
-USE_EXTENSION_MANIFEST = 1
 XPI_PKGNAME = lightning-$(LIGHTNING_VERSION).$(AB_CD).$(MOZ_PKG_PLATFORM)
 XPI_VERSION = $(LIGHTNING_VERSION)
 
 XPI_EM_ID = {e2fda1a4-762b-4020-b5ad-a41df1933103}
 
 DIST_FILES = install.rdf app.ini
 
 # Lighting version number

--- a/calendar/lightning/app-config.mk
+++ b/calendar/lightning/app-config.mk
@@ -4,11 +4,10 @@
 
 # If we are in one of the calendar directories, then make sure that files end
 # up in xpi-stage/lightning.
 ifeq (calendar,$(firstword $(subst /, ,$(subst $(topsrcdir)/,,$(srcdir)))))
 # Possibly XPI_NAME is already set, i.e in the timezones extension. Don't
 # override this.
 ifndef XPI_NAME
 XPI_NAME = lightning
-USE_EXTENSION_MANIFEST = 1
 endif
 endif

--- a/calendar/lightning/locales/Makefile.in
+++ b/calendar/lightning/locales/Makefile.in
@@ -1,14 +1,12 @@
 # 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/.
 
 # Setting this to calendar/locales sets up LOCALE_SRCDIR to the correct locale
 # directory
 relativesrcdir = calendar/locales
 
-USE_EXTENSION_MANIFEST = 1
-
 DEFINES += -DAB_CD=$(AB_CD) \
            -DTHEME=$(THEME) \
            -DLOCALE_SRCDIR=$(LOCALE_SRCDIR) \
            $(NULL)

--- a/calendar/lightning/moz.build
+++ b/calendar/lightning/moz.build
@@ -15,16 +15,19 @@ DIRS += [
 
 TEST_DIRS += ['../test']
 
 XPI_NAME = 'lightning'
 export('XPI_NAME')
 
 JAR_MANIFESTS += ['jar.mn']
 
+USE_EXTENSION_MANIFEST = True
+export('USE_EXTENSION_MANIFEST')
+
 if CONFIG['MOZ_WIDGET_TOOLKIT'] == 'windows':
     DEFINES['THEME'] = 'windows'
 elif CONFIG['MOZ_WIDGET_TOOLKIT'] == 'cocoa':
     DEFINES['THEME'] = 'osx'
 else:
     DEFINES['THEME'] = 'linux'
 
 JS_PREFERENCE_FILES += [

--- a/calendar/locales/Makefile.in
+++ b/calendar/locales/Makefile.in
@@ -1,8 +1,6 @@
 # vim:set ts=8 sw=8 sts=8 noet:
 # 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/.
 
-USE_EXTENSION_MANIFEST = 1
-
 DEFINES += -DAB_CD=$(AB_CD)

--- a/calendar/providers/gdata/Makefile.in
+++ b/calendar/providers/gdata/Makefile.in
@@ -1,13 +1,12 @@
 # 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/.
 
-USE_EXTENSION_MANIFEST = 1
 DIST_FILES = install.rdf
 XPI_PKGNAME = gdata-provider-$(GDATA_VERSION).$(AB_CD).$(MOZ_PKG_PLATFORM)
 XPI_VERSION = $(GDATA_VERSION)
 XPI_NO_UNIVERSAL = 1
 XPI_EM_ID = {a62ef8ec-5fdc-40c2-873c-223b8a6925cc}
 XPI_INSTALL_EXTENSION = $(XPI_EM_ID)
 
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version.txt)

--- a/calendar/providers/gdata/locales/Makefile.in
+++ b/calendar/providers/gdata/locales/Makefile.in
@@ -6,17 +6,15 @@ DEPTH = @DEPTH@
 topsrcdir = @top_srcdir@
 srcdir = @srcdir@
 VPATH = @srcdir@
 
 # Setting this to calendar/locales sets up LOCALE_SRCDIR to the correct locale
 # directory
 relativesrcdir = calendar/locales
 
-USE_EXTENSION_MANIFEST = 1
-
 include $(DEPTH)/config/autoconf.mk
 
 DEFINES += -DAB_CD=$(AB_CD) \
            -DLOCALE_SRCDIR=$(LOCALE_SRCDIR) \
            $(NULL)
 
 include $(topsrcdir)/config/rules.mk

deleted file mode 100644
--- a/calendar/resources/Makefile.in
+++ /dev/null
@@ -1,14 +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/.
-
-DEPTH		= @DEPTH@
-topsrcdir	= @top_srcdir@
-srcdir		= @srcdir@
-VPATH		= @srcdir@
-
-include $(DEPTH)/config/autoconf.mk
-
-USE_EXTENSION_MANIFEST = 1
-
-include $(topsrcdir)/config/rules.mk

--- a/calendar/timezones/Makefile.in
+++ b/calendar/timezones/Makefile.in
@@ -1,13 +1,12 @@
 # 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/.
 
-USE_EXTENSION_MANIFEST = 1
 DIST_FILES = install.rdf
 XPI_PKGNAME = calendar-timezones-$(TIMEZONES_VERSION)
 
 THUNDERBIRD_VERSION := $(shell cat $(topsrcdir)/mail/config/version.txt)
 SEAMONKEY_VERSION := $(shell cat $(topsrcdir)/suite/config/version.txt)
 CALENDAR_VERSION := $(shell $(PYTHON) $(topsrcdir)/calendar/lightning/build/makeversion.py $(word 1,$(MOZ_PKG_VERSION) $(THUNDERBIRD_VERSION)))
 TIMEZONES_VERSION := $(shell $(PYTHON) $(srcdir)/version.py)
 

--- a/calendar/timezones/locales/Makefile.in
+++ b/calendar/timezones/locales/Makefile.in
@@ -6,17 +6,15 @@ DEPTH = @DEPTH@
 topsrcdir = @top_srcdir@
 srcdir = @srcdir@
 VPATH = @srcdir@
 
 # Setting this to calendar/locales sets up LOCALE_SRCDIR to the correct locale
 # directory
 relativesrcdir = calendar/locales
 
-USE_EXTENSION_MANIFEST = 1
-
 include $(DEPTH)/config/autoconf.mk
 
 DEFINES += -DAB_CD=$(AB_CD) \
            -DLOCALE_SRCDIR=$(LOCALE_SRCDIR) \
            $(NULL)
 
 include $(topsrcdir)/config/rules.mk

--- a/calendar/timezones/moz.build
+++ b/calendar/timezones/moz.build
@@ -5,15 +5,18 @@
 
 DIRS += ['locales']
 
 XPI_NAME = 'calendar-timezones'
 export('XPI_NAME')
 
 JAR_MANIFESTS += ['jar.mn']
 
+USE_EXTENSION_MANIFEST = True
+export('USE_EXTENSION_MANIFEST')
+
 JS_PREFERENCE_FILES += [
     'defaults/preferences.js',
 ]
 
 FINAL_TARGET_FILES.timezones += [
     'zones.json'
 ]