diff --git a/includes/SkinOptions.php b/includes/SkinOptions.php
index 4544d26..780736c 100644
--- a/includes/SkinOptions.php
+++ b/includes/SkinOptions.php
@@ -68,6 +68,11 @@ final class SkinOptions {
 	 * @param array $options
 	 */
 	public function setMultiple( array $options ) {
+		foreach ( $options as $option => $value ) {
+			if ( !array_key_exists( $option, $this->skinOptions ) ) {
+				throw new \OutOfBoundsException( "SkinOption $option is not defined" );
+			}
+		}
 		$this->skinOptions = array_merge( $this->skinOptions, $options );
 	}
 
diff --git a/tests/phpunit/unit/SkinOptionsTest.php b/tests/phpunit/unit/SkinOptionsTest.php
index 491c500..c29cd84 100644
--- a/tests/phpunit/unit/SkinOptionsTest.php
+++ b/tests/phpunit/unit/SkinOptionsTest.php
@@ -46,4 +46,24 @@ class SkinOptionsTest extends \MediaWikiUnitTestCase {
 		] );
 		$this->assertFalse( $options->hasSkinOptions() );
 	}
+
+	/**
+	 * @covers ::get
+	 * @expectedException \OutOfBoundsException
+	 */
+	public function testGettingUnknownKeyShouldThrowException() {
+		$options = new SkinOptions();
+		$options->get( 'non_existing_key' );
+	}
+
+	/**
+	 * @covers ::get
+	 * @expectedException \OutOfBoundsException
+	*/
+	public function testSettingUnknownKeyShouldThrowException() {
+		$options = new SkinOptions();
+		$options->setMultiple( [
+			'non_existing_key' => 1
+		] );
+	}
 }