diff --git a/rapids/templates/rapids/mark_overview.html b/rapids/templates/rapids/mark_overview.html
index 1340307f..143c1398 100644
--- a/rapids/templates/rapids/mark_overview.html
+++ b/rapids/templates/rapids/mark_overview.html
@@ -12,7 +12,7 @@
 
     <ul id="question-mark-list">
         {% for question, unmarked_count in question_unmarked_map %}
-        <li data-markcount={{unmarked_count}}><a href="{% url 'rapids:mark' pk=exam.pk sk=forloop.counter0 %}">Question {{forloop.counter }}:
+        <li data-markcount={{unmarked_count|add:"0"}}><a href="{% url 'rapids:mark' pk=exam.pk sk=forloop.counter0 %}">Question {{forloop.counter }}:
                 {{ question }}</a><br />Unmarked answers: {{unmarked_count}}</li>
         {% endfor %}
     </ul>