diff --git a/src/gcal-edit-dialog.c b/src/gcal-edit-dialog.c
index 603bf921..41cc0e55 100644
--- a/src/gcal-edit-dialog.c
+++ b/src/gcal-edit-dialog.c
@@ -545,18 +545,24 @@ gcal_edit_dialog_all_day_changed (GtkWidget *widget,
 
 /* Public API */
 GtkWidget*
-gcal_edit_dialog_new (gboolean format_24h)
+gcal_edit_dialog_new (void)
 {
-  GcalEditDialog *dialog;
+  return g_object_new (GCAL_TYPE_EDIT_DIALOG, NULL);
+}
 
-  dialog = g_object_new (GCAL_TYPE_EDIT_DIALOG, NULL);
+void
+gcal_edit_dialog_set_time_format (GcalEditDialog *dialog,
+                                  gboolean        use_24h_format)
+{
+  g_return_if_fail (GCAL_IS_EDIT_DIALOG (dialog));
 
-  dialog->format_24h = format_24h;
+  if (dialog->format_24h != use_24h_format)
+  {
+    dialog->format_24h = use_24h_format;
 
-  gcal_time_selector_set_time_format (GCAL_TIME_SELECTOR (dialog->start_time_selector), format_24h);
-  gcal_time_selector_set_time_format (GCAL_TIME_SELECTOR (dialog->end_time_selector), format_24h);
-
-  return GTK_WIDGET (dialog);
+    gcal_time_selector_set_time_format (GCAL_TIME_SELECTOR (dialog->start_time_selector), dialog->format_24h);
+    gcal_time_selector_set_time_format (GCAL_TIME_SELECTOR (dialog->end_time_selector), dialog->format_24h);
+  }
 }
 
 void
diff --git a/src/gcal-edit-dialog.h b/src/gcal-edit-dialog.h
index bd192582..1dff9a1f 100644
--- a/src/gcal-edit-dialog.h
+++ b/src/gcal-edit-dialog.h
@@ -35,7 +35,7 @@ G_BEGIN_DECLS
 
 G_DECLARE_FINAL_TYPE (GcalEditDialog, gcal_edit_dialog, GCAL, EDIT_DIALOG, GtkDialog);
 
-GtkWidget*           gcal_edit_dialog_new                     (gboolean format_24h);
+GtkWidget*           gcal_edit_dialog_new                     (void);
 
 void                 gcal_edit_dialog_set_event_is_new        (GcalEditDialog *dialog,
                                                                gboolean       event_is_new);
@@ -48,6 +48,9 @@ void                 gcal_edit_dialog_set_event               (GcalEditDialog *d
 void                 gcal_edit_dialog_set_manager             (GcalEditDialog *dialog,
                                                                GcalManager    *manager);
 
+void                 gcal_edit_dialog_set_time_format         (GcalEditDialog *dialog,
+                                                               gboolean        use_24h_format);
+
 GDateTime*           gcal_edit_dialog_get_date_end            (GcalEditDialog *dialog);
 
 GDateTime*           gcal_edit_dialog_get_date_start          (GcalEditDialog *dialog);
diff --git a/src/gcal-time-selector.c b/src/gcal-time-selector.c
index 7eb9bfc3..c9711e88 100644
--- a/src/gcal-time-selector.c
+++ b/src/gcal-time-selector.c
@@ -235,7 +235,6 @@ gcal_time_selector_class_init (GcalTimeSelectorClass *klass)
 static void
 gcal_time_selector_init (GcalTimeSelector *self)
 {
-  self->format_24h = TRUE;
   self->time = g_date_time_new_now_local ();
 
   gtk_widget_init_template (GTK_WIDGET (self));
diff --git a/src/gcal-window.c b/src/gcal-window.c
index 7bcadbd6..869bf119 100644
--- a/src/gcal-window.c
+++ b/src/gcal-window.c
@@ -1351,6 +1351,8 @@ gcal_window_constructed (GObject *object)
   window->views[GCAL_WINDOW_VIEW_MONTH] = window->month_view;
   window->views[GCAL_WINDOW_VIEW_YEAR] = window->year_view;
 
+  gcal_edit_dialog_set_time_format (GCAL_EDIT_DIALOG (window->edit_dialog), use_24h_format);
+
   gcal_month_view_set_first_weekday (GCAL_MONTH_VIEW (window->views[GCAL_WINDOW_VIEW_MONTH]), get_first_weekday ());
   gcal_month_view_set_use_24h_format (GCAL_MONTH_VIEW (window->views[GCAL_WINDOW_VIEW_MONTH]), use_24h_format);