diff --git a/wagtail/wagtailimages/templates/wagtailimages/chooser/select_format.html b/wagtail/wagtailimages/templates/wagtailimages/chooser/select_format.html
index 37e9bdd96e..018f3fa751 100644
--- a/wagtail/wagtailimages/templates/wagtailimages/chooser/select_format.html
+++ b/wagtail/wagtailimages/templates/wagtailimages/chooser/select_format.html
@@ -5,7 +5,7 @@
 
 <div class="row row-flush nice-padding">
     <div class="col6">
-        {% image image max-800x600 %}
+        {% image image max-800x600 class="show-transparency" %}
     </div>
     <div class="col6">
         <form action="{% url 'wagtailimages:chooser_select_format' image.id %}" method="POST">