diff --git a/src/invenflask/templates/base.html b/src/invenflask/templates/base.html
index a2377a3..f2b7b51 100644
--- a/src/invenflask/templates/base.html
+++ b/src/invenflask/templates/base.html
@@ -66,7 +66,7 @@
         {% with messages = get_flashed_messages(with_categories=true) %}
             {% if messages %}
             {% for category, message in messages %}
-                <div class="alert alert-{{ category }}"> {{ message }} </div>
+                <div class="alert bg-{{ category }}"> {{ message }} </div>
             {% endfor %}
             {% endif %}
         {% endwith %}