diff --git a/browser/installer/windows/Makefile.in b/browser/installer/windows/Makefile.in
index 4fc19753e7b..705d22e1b81 100644
--- a/browser/installer/windows/Makefile.in
+++ b/browser/installer/windows/Makefile.in
@@ -6,8 +6,6 @@ include $(topsrcdir)/toolkit/mozapps/installer/package-name.mk
 
 CONFIG_DIR = instgen
 SFX_MODULE = $(topsrcdir)/other-licenses/7zstub/firefox/7zSD.sfx
-APP_VERSION := $(FIREFOX_VERSION)
-DEFINES += -DAPP_VERSION=$(APP_VERSION)
 
 INSTALLER_FILES = \
 	app.tag \
diff --git a/browser/installer/windows/moz.build b/browser/installer/windows/moz.build
index 895d11993cf..6d7e6e9a7fa 100644
--- a/browser/installer/windows/moz.build
+++ b/browser/installer/windows/moz.build
@@ -4,3 +4,4 @@
 # 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['FIREFOX_VERSION']
diff --git a/webapprt/win/Makefile.in b/webapprt/win/Makefile.in
index 78ad3eb04f6..37ef231a0f9 100644
--- a/webapprt/win/Makefile.in
+++ b/webapprt/win/Makefile.in
@@ -15,8 +15,6 @@ include $(topsrcdir)/toolkit/mozapps/installer/package-name.mk
 
 CONFIG_DIR = instgen
 SFX_MODULE = $(topsrcdir)/other-licenses/7zstub/firefox/7zSD.sfx
-APP_VERSION := $(FIREFOX_VERSION)
-DEFINES += -DAPP_VERSION=$(APP_VERSION)
 
 # Uninstaller
 ifdef LOCALE_MERGEDIR
diff --git a/webapprt/win/moz.build b/webapprt/win/moz.build
index c4d66a19d2c..1226d3fafb6 100644
--- a/webapprt/win/moz.build
+++ b/webapprt/win/moz.build
@@ -17,6 +17,8 @@ DEFINES['XPCOM_GLUE'] = True
 if CONFIG['DEBUG']:
     DEFINES['DEBUG'] = True
 
+DEFINES['APP_VERSION'] = CONFIG['FIREFOX_VERSION']
+
 # Statically link against the CRT
 USE_STATIC_LIBS = True