diff --git a/npmconf.js b/npmconf.js
index 7607b50..71aba7a 100644
--- a/npmconf.js
+++ b/npmconf.js
@@ -99,6 +99,7 @@ function load_(builtin, rc, cli, cb) {
   var conf = new Conf(rc)
 
   conf.usingBuiltin = !!builtin
+  conf.sources.builtin = rc.sources.builtin
   conf.add(cli, 'cli')
   conf.addEnv()
 
diff --git a/test/builtin.js b/test/builtin.js
index c94de8a..9554be0 100644
--- a/test/builtin.js
+++ b/test/builtin.js
@@ -42,7 +42,11 @@ var expectSources =
    { path: common.globalconfig,
      type: 'ini',
      data: gcData },
-  builtin: { data: biData } }
+  builtin:
+    { path: common.builtin,
+      type: 'ini',
+      data: biData }
+}
 
 test('with builtin', function (t) {
   npmconf.load(cli, common.builtin, function (er, conf) {