diff --git a/liblogdiag/ld-diagram-object.c b/liblogdiag/ld-diagram-object.c
index 684e93f..ba2c1f6 100644
--- a/liblogdiag/ld-diagram-object.c
+++ b/liblogdiag/ld-diagram-object.c
@@ -221,8 +221,12 @@ JsonObject *
 ld_diagram_object_get_storage (LdDiagramObject *self)
 {
 	g_return_val_if_fail (LD_IS_DIAGRAM_OBJECT (self), NULL);
+
 	if (!self->priv->storage)
+	{
 		self->priv->storage = json_object_new ();
+		g_object_notify (G_OBJECT (self), "storage");
+	}
 	return self->priv->storage;
 }
 
@@ -245,6 +249,8 @@ ld_diagram_object_set_storage (LdDiagramObject *self, JsonObject *storage)
 		self->priv->storage = json_object_ref (storage);
 	else
 		self->priv->storage = NULL;
+
+	g_object_notify (G_OBJECT (self), "storage");
 }
 
 /**
diff --git a/liblogdiag/ld-diagram.c b/liblogdiag/ld-diagram.c
index cd483ec..46f94df 100644
--- a/liblogdiag/ld-diagram.c
+++ b/liblogdiag/ld-diagram.c
@@ -803,12 +803,19 @@ ld_diagram_end_user_action (LdDiagram *self)
 			(self->priv->undo_stack, self->priv->undo_stack);
 }
 
+static void
+action_finalize_notify_cb (ObjectActionData *data, LdDiagram *self)
+{
+	data->self = NULL;
+}
+
 static void
 on_object_action_remove (gpointer user_data)
 {
 	ObjectActionData *data;
 
 	data = user_data;
+	g_return_if_fail (data->self != NULL);
 	ld_diagram_remove_object (data->self, data->object);
 }
 
@@ -818,6 +825,7 @@ on_object_action_insert (gpointer user_data)
 	ObjectActionData *data;
 
 	data = user_data;
+	g_return_if_fail (data->self != NULL);
 	ld_diagram_insert_object (data->self, data->object, data->pos);
 }
 
@@ -827,7 +835,8 @@ on_object_action_destroy (gpointer user_data)
 	ObjectActionData *data;
 
 	data = user_data;
-	g_object_unref (data->self);
+	g_object_weak_unref (G_OBJECT (data->self),
+		(GWeakNotify) action_finalize_notify_cb, data);
 	g_object_unref (data->object);
 	g_slice_free (ObjectActionData, data);
 }
@@ -891,7 +900,9 @@ ld_diagram_insert_object (LdDiagram *self, LdDiagramObject *object, gint pos)
 	install_object (object, self);
 
 	action_data = g_slice_new (ObjectActionData);
-	action_data->self = g_object_ref (self);
+	action_data->self = self;
+	g_object_weak_ref (G_OBJECT (self),
+		(GWeakNotify) action_finalize_notify_cb, action_data);
 	action_data->object = g_object_ref (object);
 	action_data->pos = pos;
 
@@ -938,7 +949,9 @@ ld_diagram_remove_object (LdDiagram *self, LdDiagramObject *object)
 	uninstall_object (object, self);
 
 	action_data = g_slice_new (ObjectActionData);
-	action_data->self = g_object_ref (self);
+	action_data->self = self;
+	g_object_weak_ref (G_OBJECT (self),
+		(GWeakNotify) action_finalize_notify_cb, action_data);
 	action_data->object = g_object_ref (object);
 	action_data->pos = pos;
 
diff --git a/liblogdiag/ld-library.c b/liblogdiag/ld-library.c
index 13242a1..8f07720 100644
--- a/liblogdiag/ld-library.c
+++ b/liblogdiag/ld-library.c
@@ -378,7 +378,10 @@ ld_library_load_cb (const gchar *base, const gchar *filename, gpointer userdata)
 
 	cat = load_category (data->self, filename, base);
 	if (cat)
+	{
 		ld_library_insert_category (data->self, cat, -1);
+		g_object_unref (cat);
+	}
 
 	data->changed = TRUE;
 	return TRUE;
diff --git a/liblogdiag/ld-symbol-category.c b/liblogdiag/ld-symbol-category.c
index d8150dc..4c35c4c 100644
--- a/liblogdiag/ld-symbol-category.c
+++ b/liblogdiag/ld-symbol-category.c
@@ -325,8 +325,11 @@ ld_symbol_category_remove_symbol (LdSymbolCategory *self,
 	g_return_if_fail (LD_IS_SYMBOL_CATEGORY (self));
 	g_return_if_fail (LD_IS_SYMBOL (symbol));
 
-	g_object_unref (symbol);
-	self->priv->symbols = g_slist_remove (self->priv->symbols, symbol);
+	if (g_slist_find (self->priv->symbols, symbol))
+	{
+		self->priv->symbols = g_slist_remove (self->priv->symbols, symbol);
+		g_object_unref (symbol);
+	}
 }
 
 /**
@@ -378,9 +381,12 @@ ld_symbol_category_remove_subcategory (LdSymbolCategory *self,
 	g_return_if_fail (LD_IS_SYMBOL_CATEGORY (self));
 	g_return_if_fail (LD_IS_SYMBOL_CATEGORY (category));
 
-	g_object_unref (category);
-	self->priv->subcategories
-		= g_slist_remove (self->priv->subcategories, category);
+	if (g_slist_find (self->priv->subcategories, category))
+	{
+		self->priv->subcategories
+			= g_slist_remove (self->priv->subcategories, category);
+		g_object_unref (category);
+	}
 }
 
 /**