diff --git a/demos/gtk-demo/application.c b/demos/gtk-demo/application.c
index e1aae430b2..53be2b10d0 100644
--- a/demos/gtk-demo/application.c
+++ b/demos/gtk-demo/application.c
@@ -503,13 +503,13 @@ demo_application_window_unrealize (GtkWidget *widget)
 }
 
 static void
-demo_application_window_destroy (GtkWidget *widget)
+demo_application_window_dispose (GObject *object)
 {
-  DemoApplicationWindow *window = (DemoApplicationWindow *)widget;
+  DemoApplicationWindow *window = (DemoApplicationWindow *)object;
 
   demo_application_window_store_state (window);
 
-  GTK_WIDGET_CLASS (demo_application_window_parent_class)->destroy (widget);
+  G_OBJECT_CLASS (demo_application_window_parent_class)->dispose (object);
 }
 
 static void
@@ -519,11 +519,11 @@ demo_application_window_class_init (DemoApplicationWindowClass *class)
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (class);
 
   object_class->constructed = demo_application_window_constructed;
+  object_class->dispose = demo_application_window_dispose;
 
   widget_class->size_allocate = demo_application_window_size_allocate;
   widget_class->realize = demo_application_window_realize;
   widget_class->unrealize = demo_application_window_unrealize;
-  widget_class->destroy = demo_application_window_destroy;
 
   gtk_widget_class_set_template_from_resource (widget_class, "/application_demo/application.ui");
   gtk_widget_class_bind_template_child (widget_class, DemoApplicationWindow, message);
diff --git a/demos/gtk-demo/constraints.c b/demos/gtk-demo/constraints.c
index f2f9076fa3..306d4b340c 100644
--- a/demos/gtk-demo/constraints.c
+++ b/demos/gtk-demo/constraints.c
@@ -21,23 +21,24 @@ struct _SimpleGrid
 G_DEFINE_TYPE (SimpleGrid, simple_grid, GTK_TYPE_WIDGET)
 
 static void
-simple_grid_destroy (GtkWidget *widget)
+simple_grid_dispose (GObject *object)
 {
-  SimpleGrid *self = SIMPLE_GRID (widget);
+  SimpleGrid *self = SIMPLE_GRID (object);
 
   g_clear_pointer (&self->button1, gtk_widget_destroy);
   g_clear_pointer (&self->button2, gtk_widget_destroy);
   g_clear_pointer (&self->button3, gtk_widget_destroy);
 
-  GTK_WIDGET_CLASS (simple_grid_parent_class)->destroy (widget);
+  G_OBJECT_CLASS (simple_grid_parent_class)->dispose (object);
 }
 
 static void
 simple_grid_class_init (SimpleGridClass *klass)
 {
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
-  widget_class->destroy = simple_grid_destroy;
+  object_class->dispose = simple_grid_dispose;
 
   gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_CONSTRAINT_LAYOUT);
 }
diff --git a/demos/gtk-demo/constraints2.c b/demos/gtk-demo/constraints2.c
index cdaaa85088..bd2f373e0f 100644
--- a/demos/gtk-demo/constraints2.c
+++ b/demos/gtk-demo/constraints2.c
@@ -22,23 +22,24 @@ struct _InteractiveGrid
 G_DEFINE_TYPE (InteractiveGrid, interactive_grid, GTK_TYPE_WIDGET)
 
 static void
-interactive_grid_destroy (GtkWidget *widget)
+interactive_grid_dispose (GObject *object)
 {
-  InteractiveGrid *self = INTERACTIVE_GRID (widget);
+  InteractiveGrid *self = INTERACTIVE_GRID (object);
 
   g_clear_pointer (&self->button1, gtk_widget_destroy);
   g_clear_pointer (&self->button2, gtk_widget_destroy);
   g_clear_pointer (&self->button3, gtk_widget_destroy);
 
-  GTK_WIDGET_CLASS (interactive_grid_parent_class)->destroy (widget);
+  G_OBJECT_CLASS (interactive_grid_parent_class)->dispose (object);
 }
 
 static void
 interactive_grid_class_init (InteractiveGridClass *klass)
 {
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
-  widget_class->destroy = interactive_grid_destroy;
+  object_class->dispose = interactive_grid_dispose;
 
   gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_CONSTRAINT_LAYOUT);
 }
diff --git a/demos/gtk-demo/constraints3.c b/demos/gtk-demo/constraints3.c
index 01d81a48d2..a534a905f7 100644
--- a/demos/gtk-demo/constraints3.c
+++ b/demos/gtk-demo/constraints3.c
@@ -20,23 +20,24 @@ struct _VflGrid
 G_DEFINE_TYPE (VflGrid, vfl_grid, GTK_TYPE_WIDGET)
 
 static void
-vfl_grid_destroy (GtkWidget *widget)
+vfl_grid_dispose (GObject *object)
 {
-  VflGrid *self = VFL_GRID (widget);
+  VflGrid *self = VFL_GRID (object);
 
   g_clear_pointer (&self->button1, gtk_widget_destroy);
   g_clear_pointer (&self->button2, gtk_widget_destroy);
   g_clear_pointer (&self->button3, gtk_widget_destroy);
 
-  GTK_WIDGET_CLASS (vfl_grid_parent_class)->destroy (widget);
+  G_OBJECT_CLASS (vfl_grid_parent_class)->dispose (object);
 }
 
 static void
 vfl_grid_class_init (VflGridClass *klass)
 {
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
   GtkWidgetClass *widget_class = GTK_WIDGET_CLASS (klass);
 
-  widget_class->destroy = vfl_grid_destroy;
+  object_class->dispose = vfl_grid_dispose;
 
   gtk_widget_class_set_layout_manager_type (widget_class, GTK_TYPE_CONSTRAINT_LAYOUT);
 }