diff --git a/browser/config/mozconfig b/browser/config/mozconfig
index 2dd474c0269..b4d7a1ba8a0 100644
--- a/browser/config/mozconfig
+++ b/browser/config/mozconfig
@@ -2,5 +2,4 @@
 #  . $topsrcdir/browser/config/mozconfig
 # to the top of your mozconfig file.
 
-mk_add_options MOZ_CO_PROJECT=browser
 ac_add_options --enable-application=browser
diff --git a/xulrunner/config/mozconfig b/xulrunner/config/mozconfig
index 0ec33a80aaa..7e8f8074923 100644
--- a/xulrunner/config/mozconfig
+++ b/xulrunner/config/mozconfig
@@ -1,7 +1,5 @@
-
 # This file specifies the build flags for XULRunner.  You can use it by adding:
 #  . $topsrcdir/xulrunner/config/mozconfig
 # to the top of your mozconfig file.
 
-mk_add_options MOZ_CO_PROJECT=xulrunner
 ac_add_options --enable-application=xulrunner