diff --git a/test/strings.js b/test/strings.js
index 13a7a13a..102600bb 100644
--- a/test/strings.js
+++ b/test/strings.js
@@ -435,6 +435,8 @@ $(document).ready(function() {
   });
 
   test('String: underscored', function(){
+    equal(_('oneAtATime').underscored(), 'one_at_a_time');
+    equal(_('oneAtATime AnotherWordAtATime').underscored(), 'one_at_a_time_another_word_at_a_time');
     equal(_('the-underscored-string-method').underscored(), 'the_underscored_string_method');
     equal(_('theUnderscoredStringMethod').underscored(), 'the_underscored_string_method');
     equal(_('TheUnderscoredStringMethod').underscored(), 'the_underscored_string_method');
diff --git a/underscored.js b/underscored.js
index b9d16283..a073faaf 100644
--- a/underscored.js
+++ b/underscored.js
@@ -1,5 +1,5 @@
 var trim = require('./trim');
 
 module.exports = function underscored(str) {
-  return trim(str).replace(/([a-z\d])([A-Z]+)/g, '$1_$2').replace(/[-\s]+/g, '_').toLowerCase();
+  return trim(str).replace(/([a-z\d])([A-Z]+)/g, '$1_$2').replace(/([A-Z\d]+)([A-Z][a-z])/g,'$1_$2').replace(/[-\s]+/g, '_').toLowerCase();
 };