diff --git a/data/ui/time-selector.ui b/data/ui/time-selector.ui
index 1e2ab422..c3b82ae6 100644
--- a/data/ui/time-selector.ui
+++ b/data/ui/time-selector.ui
@@ -55,10 +55,14 @@
       </packing>
     </child>
     <child>
-      <object class="GtkComboBox" id="period_combo">
-        <property name="visible">True</property>
+      <object class="GtkComboBoxText" id="period_combo">
+        <property name="visible">False</property>
         <property name="can_focus">False</property>
         <property name="valign">center</property>
+        <items>
+          <item translatable="yes">AM</item>
+          <item translatable="yes">PM</item>
+        </items>
       </object>
       <packing>
         <property name="left_attach">3</property>
diff --git a/src/gcal-time-selector.c b/src/gcal-time-selector.c
index d1070c95..e5e3afd6 100644
--- a/src/gcal-time-selector.c
+++ b/src/gcal-time-selector.c
@@ -146,6 +146,7 @@ gcal_time_selector_constructed (GObject *object)
   g_object_ref (priv->minute_spin);
 
   priv->period_combo = (GtkWidget*) gtk_builder_get_object (builder, "period_combo");
+  gtk_widget_set_visible (priv->period_combo, !priv->format_24h);
   g_object_ref (priv->period_combo);
 
   g_object_unref (builder);