diff --git a/.gitmodules b/.gitmodules
index 960bf4c..9d66ab9 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "external/hosts"]
 	path = external/hosts
 	url = https://github.com/StevenBlack/hosts
+[submodule "external/user.js"]
+	path = external/user.js
+	url = https://github.com/pyllyukko/user.js
diff --git a/build.sh b/build.sh
index ba89bd6..ed08e02 100644
--- a/build.sh
+++ b/build.sh
@@ -4,6 +4,12 @@ buildHash=$(git rev-parse --short HEAD)
 ##update submodules
 git submodule update --init --recursive
 
+##add locked_user.js from pyllyukko/user.js
+cd external/user.js
+make locked_user.js
+cp locked_user.js ../../include/usr/lib/firefox/mozilla.cfg
+cd ../..
+
 ##add hosts from stevenblack/hosts
 cp external/hosts/hosts include/etc/hosts
 
diff --git a/external/user.js b/external/user.js
new file mode 160000
index 0000000..d6ce4eb
--- /dev/null
+++ b/external/user.js
@@ -0,0 +1 @@
+Subproject commit d6ce4ebf9e30e846b9e383384f7a20d121fb4030
diff --git a/include/usr/lib/firefox/defaults/pref/local-settings.js b/include/usr/lib/firefox/defaults/pref/local-settings.js
new file mode 100644
index 0000000..8712516
--- /dev/null
+++ b/include/usr/lib/firefox/defaults/pref/local-settings.js
@@ -0,0 +1,2 @@
+pref("general.config.obscure_value", 0);
+pref("general.config.filename", "mozilla.cfg");