--- a/browser/app/Makefile.in
+++ b/browser/app/Makefile.in
@@ -71,17 +71,17 @@ endif
 
 libs:: $(srcdir)/profile/prefs.js
 	$(INSTALL) $(IFLAGS1) $^ $(FINAL_TARGET)/defaults/profile
 
 ifndef LIBXUL_SDK
 # channel-prefs.js is handled separate from other prefs due to bug 756325
 libs:: $(srcdir)/profile/channel-prefs.js
 	$(NSINSTALL) -D $(DIST)/bin/defaults/pref
-	$(call py_action,preprocessor,$(PREF_PPFLAGS) $(ACDEFINES) $^ -o $(DIST)/bin/defaults/pref/channel-prefs.js)
+	$(call py_action,preprocessor,-Fsubstitution $(PREF_PPFLAGS) $(ACDEFINES) $^ -o $(DIST)/bin/defaults/pref/channel-prefs.js)
 endif
 
 libs:: $(srcdir)/blocklist.xml
 	$(INSTALL) $(IFLAGS1) $^ $(FINAL_TARGET)
 
 ifeq (cocoa,$(MOZ_WIDGET_TOOLKIT))
 
 MAC_APP_NAME = $(MOZ_APP_DISPLAYNAME)

--- a/browser/app/profile/channel-prefs.js
+++ b/browser/app/profile/channel-prefs.js
@@ -1,6 +1,5 @@
-#filter substitution
 /* 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/. */
 
 pref("app.update.channel", "@MOZ_UPDATE_CHANNEL@");