diff --git a/js/collapse.js b/js/collapse.js
index bdd7d8547655..cd8f38439b18 100644
--- a/js/collapse.js
+++ b/js/collapse.js
@@ -58,7 +58,7 @@
     var complete = function () {
       this.$element
         .removeClass('collapsing')
-        .addClass('in')
+        .addClass('collapse in')
         [dimension]('auto')
       this.transitioning = 0
       this.$element.trigger('shown.bs.collapse')