--- a/browser/locales/Makefile.in
+++ b/browser/locales/Makefile.in
@@ -18,16 +18,20 @@ PWD := $(CURDIR)
 
 # These are defaulted to be compatible with the files the wget-en-US target
 # pulls. You may override them if you provide your own files.
 ZIP_IN ?= $(ABS_DIST)/$(PACKAGE)
 WIN32_INSTALLER_IN ?= $(ABS_DIST)/$(PKG_INST_PATH)$(PKG_INST_BASENAME).exe
 RETRIEVE_WINDOWS_INSTALLER = 1
 
 MOZ_LANGPACK_EID=langpack-$(AB_CD)@firefox.mozilla.org
+# For Nightly, we know where to get the builds from to do local repacks
+ifdef NIGHTLY_BUILD
+export EN_US_BINARY_URL ?= https://archive.mozilla.org/pub/firefox/nightly/latest-mozilla-central
+endif
 
 L10N_PREF_JS_EXPORTS = $(call MERGE_FILE,firefox-l10n.js)
 L10N_PREF_JS_EXPORTS_PATH = $(FINAL_TARGET)/$(PREF_DIR)
 L10N_PREF_JS_EXPORTS_FLAGS = $(PREF_PPFLAGS) --silence-missing-directive-warnings
 PP_TARGETS += L10N_PREF_JS_EXPORTS
 
 ifneq (,$(filter cocoa,$(MOZ_WIDGET_TOOLKIT)))
 MOZ_PKG_MAC_DSSTORE=$(ABS_DIST)/branding/dsstore