diff --git a/common.c b/common.c
index 6d73130..8d8dcf6 100644
--- a/common.c
+++ b/common.c
@@ -553,14 +553,11 @@ struct config_schema
 	const char *default_;               ///< Default as a configuration snippet
 
 	/// Check if the new value can be accepted.
-	/// If this is not defined, only "type" and having a default is considered.
-	bool (*validate) (struct config_item_ *, const struct config_item_ *);
+	/// In addition to this, "type" and having a default is considered.
+	bool (*validate) (const struct config_item_ *, struct error **e);
 
-	/// The value has changed. Only appliable to objects.
+	/// The value has changed
 	void (*on_changed) (struct config_item_ *);
-
-	/// Free any resources located in "item->user_data"
-	void (*on_destroy) (struct config_item_ *item);
 };
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
@@ -608,9 +605,6 @@ config_item_free (struct config_item_ *self)
 static void
 config_item_destroy (struct config_item_ *self)
 {
-	if (self->schema && self->schema->on_destroy)
-		self->schema->on_destroy (self);
-
 	config_item_free (self);
 	free (self);
 }
@@ -703,16 +697,18 @@ config_schema_accepts_type
 
 static bool
 config_item_validate_by_schema (struct config_item_ *self,
-	struct config_item_ *source, struct config_schema *schema, struct error **e)
+	struct config_schema *schema, struct error **e)
 {
-	// Otherwise we check the type and validate the item
-	if (!config_schema_accepts_type (schema, source->type))
+	struct error *error = NULL;
+	if (!config_schema_accepts_type (schema, self->type))
 		error_set (e, "invalid type of value, expected: %s%s",
 			config_item_type_name (schema->type),
 			!schema->default_ ? " (or null)" : "");
-	else if (schema->validate && !schema->validate (self, source))
-		// XXX: perhaps "schema->validate" could provide a message for us?
-		error_set (e, "invalid value");
+	else if (schema->validate && !schema->validate (self, &error))
+	{
+		error_set (e, "%s: %s", "invalid value", error->message);
+		error_free (error);
+	}
 	else
 		return true;
 	return false;
@@ -730,7 +726,7 @@ config_item_set_from (struct config_item_ *self, struct config_item_ *source,
 		return true;
 	}
 
-	if (!config_item_validate_by_schema (self, source, schema, e))
+	if (!config_item_validate_by_schema (source, schema, e))
 		return false;
 
 	// Make sure the string subtype fits the schema
@@ -1415,48 +1411,58 @@ end:
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
+// XXX: this thing is ugly in concept
+
+static void
+config_schema_fix_value
+	(struct config_schema *schema, struct config_item_ *object)
+{
+	struct config_item_ *item =
+		str_map_find (&object->value.object, schema->name);
+
+	bool replace = true;
+	if (item)
+	{
+		struct error *e = NULL;
+		replace = !config_item_validate_by_schema (item, schema, &e);
+		if (e)
+		{
+			print_error ("resetting configuration item "
+				"`%s' to default: %s", schema->name, e->message);
+			error_free (e);
+		}
+	}
+
+	if (replace)
+	{
+		struct error *e = NULL;
+		struct config_item_ *default_ = config_item_parse
+			(schema->default_, strlen (schema->default_), true, &e);
+		if (e || !config_item_validate_by_schema (default_, schema, &e))
+			exit_fatal ("invalid default for `%s': %s",
+				schema->name, e->message);
+
+		config_item_move (item, default_);
+		str_map_set (&object->value.object, schema->name, default_);
+	}
+
+	// Make sure the string subtype fits the schema
+	if (config_item_type_is_string (item->type)
+	 && config_item_type_is_string (schema->type))
+		item->type = schema->type;
+
+	item->schema = schema;
+	if (schema->on_changed)
+		schema->on_changed (item);
+}
+
 static void
 config_schema_apply_to_object
 	(struct config_schema *schema_array, struct config_item_ *object)
 {
 	hard_assert (object->type == CONFIG_ITEM_OBJECT);
 	while (schema_array->name)
-	{
-		struct config_schema *schema = schema_array++;
-		struct config_item_ *item =
-			str_map_find (&object->value.object, schema->name);
-
-		bool make_new = true;
-		if (item)
-		{
-			struct error *e = NULL;
-			make_new = !config_item_validate_by_schema
-				(NULL, item, schema, &e);
-			if (e)
-			{
-				print_error ("resetting configuration item "
-					"`%s' to defaults: %s", schema->name, e->message);
-				error_free (e);
-			}
-		}
-
-		if (make_new)
-		{
-			struct error *e = NULL;
-			struct config_item_ *default_ = config_item_parse
-				(schema->default_, strlen (schema->default_), true, &e);
-			if (e)
-				exit_fatal ("invalid default: %s", e->message);
-
-			config_item_move (item, default_);
-		}
-
-		item->type = schema->type;
-		item->schema = schema;
-
-		if (schema->on_changed)
-			schema->on_changed (item);
-	}
+		config_schema_fix_value (schema_array++, object);
 }
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -