diff --git a/index.js b/index.js
index 456aeba6e..0b0a36d55 100755
--- a/index.js
+++ b/index.js
@@ -196,7 +196,8 @@ NYC.prototype.addAllFiles = function () {
 
   this._loadAdditionalModules()
 
-  glob.sync('**/*.js', {cwd: this.cwd, nodir: true, ignore: this.exclude}).forEach(function (filename) {
+  var pattern = '**/*{' + this.extensions.join() + '}'
+  glob.sync(pattern, {cwd: this.cwd, nodir: true, ignore: this.exclude}).forEach(function (filename) {
     var obj = _this.addFile(path.join(_this.cwd, filename))
     if (obj.instrument) {
       module._compile(
diff --git a/test/fixtures/not-loaded.es6 b/test/fixtures/not-loaded.es6
new file mode 100644
index 000000000..d1db34ee3
--- /dev/null
+++ b/test/fixtures/not-loaded.es6
@@ -0,0 +1,2 @@
+var i = 3 + 5
+i++
diff --git a/test/src/nyc-test.js b/test/src/nyc-test.js
index 4fa266d70..d17df1827 100644
--- a/test/src/nyc-test.js
+++ b/test/src/nyc-test.js
@@ -546,6 +546,33 @@ describe('nyc', function () {
       return done()
     })
 
+    it('outputs an empty coverage report for multiple configured extensions', function (done) {
+      var nyc = new NYC({
+        cwd: fixtures
+      })
+      nyc.reset()
+      nyc.addAllFiles()
+
+      var notLoadedPath1 = path.join(fixtures, './not-loaded.es6')
+      var notLoadedPath2 = path.join(fixtures, './not-loaded.js')
+      var reports = _.filter(nyc._loadReports(), function (report) {
+        var apr = ap(report)
+        return apr[notLoadedPath1] || apr[notLoadedPath2]
+      })
+
+      reports.length.should.equal(1)
+
+      var report1 = reports[0][notLoadedPath1]
+      report1.s['1'].should.equal(0)
+      report1.s['2'].should.equal(0)
+
+      var report2 = reports[0][notLoadedPath2]
+      report2.s['1'].should.equal(0)
+      report2.s['2'].should.equal(0)
+
+      return done()
+    })
+
     it('tracks coverage appropriately once the file is required', function (done) {
       var nyc = (new NYC({
         cwd: fixtures