--- a/mail/locales/Makefile.in
+++ b/mail/locales/Makefile.in
@@ -183,17 +183,17 @@ ifeq (WINNT, $(OS_ARCH))
 	   "$(UPLOAD_DIR)/$(PKG_INST_PATH)$(PKG_INST_BASENAME).exe"
 endif
 # Set the permissions that the folders will have in ftp once uploaded
 	chmod -vR 775 $(UPLOAD_DIR)
 
 merge-%:
 ifdef LOCALE_MERGEDIR
 	$(RM) -rf $(LOCALE_MERGEDIR)
-	MACOSX_DEPLOYMENT_TARGET= compare-locales -m $(LOCALE_MERGEDIR) $(srcdir)/l10n.ini $(L10NBASEDIR) $*
+	$(MOZILLA_SRCDIR)/mach compare-locales --merge-dir $(LOCALE_MERGEDIR) --l10n-ini $(srcdir)/l10n.ini $*
 endif
 	@echo
 
 # test target, depends on make package
 # try to repack x-test, with just toolkit/defines.inc being there
 l10n-check::
 	$(RM) -rf x-test
 	$(NSINSTALL) -D x-test/toolkit