diff --git a/nested_inline/admin.py b/nested_inline/admin.py
index 68daca9..2fe3c47 100644
--- a/nested_inline/admin.py
+++ b/nested_inline/admin.py
@@ -407,6 +407,8 @@ def media(self):
             js.extend(['urlify.js', 'prepopulate%s.js' % extra])
         if self.filter_vertical or self.filter_horizontal:
             js.extend(['SelectBox.js', 'SelectFilter2.js'])
+        if self.classes and 'collapse' in self.classes:
+            js.append('collapse%s.js' % extra)
         return forms.Media(js=[static('admin/js/%s' % url) for url in js])
 
     def get_formsets_with_inlines(self, request, obj=None):