diff --git a/src/openforms/js/components/admin/forms/Fieldset.js b/src/openforms/js/components/admin/forms/Fieldset.js
index 0b407dd58e..1df589172e 100644
--- a/src/openforms/js/components/admin/forms/Fieldset.js
+++ b/src/openforms/js/components/admin/forms/Fieldset.js
@@ -63,7 +63,7 @@ const Fieldset = ({
     </h2>
   ) : null;
   const className = classNames('module', 'aligned', extraClassName, {
-    'collapse in': collapsible,
+    'collapse in show': collapsible,
     collapsed: collapsed,
   });