diff --git a/BasicObject.php b/BasicObject.php
index a0ddc01..e5426d6 100644
--- a/BasicObject.php
+++ b/BasicObject.php
@@ -99,6 +99,17 @@ public static function with_disabled_cache($callback) {
 	 */
 //	abstract protected static function table_name();
 
+	/**
+	 * Array with names of extra fields supported by this model.
+	 * When using `update_attributes` all fields from this array will be
+	 * set on the instance it present in data. Useful when combied with
+	 * `__set`, e.g. setting `bar` affects `foo` but `bar` isn't present
+	 * in the database table.
+	 */
+	protected static function extra_fields(){
+		return [];
+	}
+
 	/**
 	 * Returns the table name associated with this class.
 	 * @return The name of the table this class is associated with.
@@ -1125,13 +1136,14 @@ private static function handle_params($params, &$joins, &$wheres, &$order, &$tab
 	 *            create: If true new objects can be created if ID is missing or null, otherwise null
 	 *                    will be returned when the object should've been created.
 	 */
-	public static function update_attributes($array, $options=array()) {
+	public static function update_attributes(array $array, $options=[]) {
 		$defaults = array(
 			'empty_to_null' => true,
 			'commit' => false,
 			'permit' => false,
 			'create' => true,
 		);
+		$extra_fields = static::extra_fields();
 		$options = array_merge($defaults, $options);
 		if ( $options['empty_to_null'] == true || is_array($options['empty_to_null']) ){
 			$keys = $options['empty_to_null'];
@@ -1148,7 +1160,9 @@ public static function update_attributes($array, $options=array()) {
 		/* remove unpermitted keys */
 		if ( is_array($options['permit']) ){
 			$permit = array_merge($options['permit'], array('id', static::id_name()));
-			$array = array_intersect_key($array, array_combine($permit, $permit));
+			$permit = array_combine($permit, $permit);
+			$array = array_intersect_key($array, $permit);
+			$extra_fields = array_intersect($extra_fields, $permit);
 		}
 
 		$obj = new static($array);
@@ -1176,6 +1190,13 @@ public static function update_attributes($array, $options=array()) {
 			return null;
 		}
 
+		/* call __set for all extra fields */
+		foreach ( $extra_fields as $key ){
+			if ( array_key_exists($key, $array) ){
+				$obj->$key = $array[$key];
+			}
+		}
+
 		if(!isset($options["commit"]) || $options["commit"] == true) {
 			$obj->commit();
 		}
diff --git a/tests/models/ModelExtraFields.php b/tests/models/ModelExtraFields.php
new file mode 100644
index 0000000..03bfb08
--- /dev/null
+++ b/tests/models/ModelExtraFields.php
@@ -0,0 +1,31 @@
+<?php
+
+class ModelExtraFields extends BasicObject {
+	protected static function table_name() {
+		return 'model1';
+	}
+
+	protected static function extra_fields() {
+		return ['int2'];
+	}
+
+	public function __get($key) {
+		switch ( $key ){
+			case 'int2':
+				return $this->int1 - 10;
+				break;
+			default:
+				return parent::__get($key);
+		}
+	}
+
+	public function __set($key, $value) {
+		switch ( $key ){
+			case 'int2':
+				$this->int1 = $value + 10;
+				break;
+			default:
+				parent::__set($key, $value);
+		}
+	}
+};
diff --git a/tests/suites/BasicObject/ExtraFieldsTest.php b/tests/suites/BasicObject/ExtraFieldsTest.php
new file mode 100644
index 0000000..05810d8
--- /dev/null
+++ b/tests/suites/BasicObject/ExtraFieldsTest.php
@@ -0,0 +1,37 @@
+<?php
+
+class ExtraFieldsTest extends DatabaseTestCase {
+	public function testSetCalled() {
+		$data = ['int2' => 5];
+		$model = ModelExtraFields::update_attributes($data, [
+			'commit' => false,
+		]);
+		$this->assertEquals(15, $model->int1, 'int1 should be set via int2');
+	}
+
+	public function testOrder() {
+		$data = ['int1' => 4, 'int2' => 5];
+		$model = ModelExtraFields::update_attributes($data, [
+			'commit' => false,
+		]);
+		$this->assertEquals(15, $model->int1, 'base fields should be set before extra fields');
+	}
+
+	public function testPermitNegative() {
+		$data = ['int1' => 4, 'int2' => 5];
+		$model = ModelExtraFields::update_attributes($data, [
+			'commit' => false,
+			'permit' => ['int1'],
+		]);
+		$this->assertEquals(4, $model->int1, 'int2 should be ignored if not listed in permit');
+	}
+
+	public function testPermitPositive() {
+		$data = ['int1' => 4, 'int2' => 5];
+		$model = ModelExtraFields::update_attributes($data, [
+			'commit' => false,
+			'permit' => ['int2'],
+		]);
+		$this->assertEquals(15, $model->int1, 'int2 should be used when listed in permit');
+	}
+}
diff --git a/tests/tests.sh b/tests/tests.sh
index 83aeaf0..75db250 100755
--- a/tests/tests.sh
+++ b/tests/tests.sh
@@ -1,11 +1,16 @@
 #!/bin/sh
 
-set +e
+set -e
 cd `dirname $0`
 
-echo -e "Running tests without cache\n"
+echo "Running tests without cache"
+echo
 ./phpunit --bootstrap "no_cache.php" --exclude-group cache $@
 
-echo -e "\n----------------------\n"
-echo -e "Running tests with cache\n"
+echo
+echo "----------------------"
+echo
+echo "Running tests with cache"
+echo
+
 ./phpunit --bootstrap "with_cache.php" $@