diff --git a/biscuit/apps/chronos/templates/chronos/edit_substitution.html b/biscuit/apps/chronos/templates/chronos/edit_substitution.html
index c205e848dffab59853326f3fb8e93630cd49515f..47a62446b0a7f11c4960e93feddfa55b7c0c3452 100644
--- a/biscuit/apps/chronos/templates/chronos/edit_substitution.html
+++ b/biscuit/apps/chronos/templates/chronos/edit_substitution.html
@@ -22,7 +22,7 @@
   <form method="post">
     {% csrf_token %}
     {% bootstrap_form edit_substitution_form %}
-    <button type="submit" class="btn btn-secondary">
+    <button type="submit" class="btn btn-dark">
       {% blocktrans %}Save{% endblocktrans %}
     </button>
   </form>
diff --git a/biscuit/apps/chronos/templates/chronos/tt_week.html b/biscuit/apps/chronos/templates/chronos/tt_week.html
index 97c2a21e3c37138404c7558dc50a0eebc2efaf40..b90aec590511853e51e0fb410af77e7da4523dff 100644
--- a/biscuit/apps/chronos/templates/chronos/tt_week.html
+++ b/biscuit/apps/chronos/templates/chronos/tt_week.html
@@ -15,7 +15,7 @@
     <ul id="timetable_select_form">
       {{ select_form.as_ul }}
     </ul>
-    <button type="submit" class="btn btn-secondary">
+    <button type="submit" class="btn btn-dark">
       {% blocktrans %}Select{% endblocktrans %}
     </button>
   </form>