diff --git a/mozilla/mail/locales/Makefile.in b/mozilla/mail/locales/Makefile.in
index 279ac15b5e3..a097ab5b5e7 100644
--- a/mozilla/mail/locales/Makefile.in
+++ b/mozilla/mail/locales/Makefile.in
@@ -106,7 +106,7 @@ repackage-win32-installer: $(WIN32_INSTALLER_IN)
 	  $(DIST)/l10n-temp-stage/installer.inc
 	$(PERL) $(topsrcdir)/config/preprocessor.pl $(DEFINES) $(ACDEFINES) \
 	  -I$(DIST)/l10n-temp-stage/installer.inc \
-	  -I$(call EXPAND_LOCALE_SRCDIR,toolkit/locales)/installer/windows/install.in \
+	  -I$(call EXPAND_LOCALE_SRCDIR,toolkit/locales)/installer/windows/install.it \
 	  $(topsrcdir)/mail/installer/windows/install.it > $(DIST)/l10n-stage/install.ini
 	cd $(DIST)/l10n-stage && \
 	  $(CYGWIN_WRAPPER) 7z a -tz7 ../l10n-temp-stage/app.7z *.* -mx -m0=BCJ2 -m1=LZMA:d24 -m2=LZMA:d19 -m3=LZMA:d19 -mb0:1 -mb0s1:2 -mb0s2:3