diff --git a/src/Services/MultiDomain.php b/src/Services/MultiDomain.php
index 612137c..33f6a34 100644
--- a/src/Services/MultiDomain.php
+++ b/src/Services/MultiDomain.php
@@ -30,7 +30,13 @@ abstract class MultiDomain implements ServiceInterface
         return false;
     }
 
+    /**
+     * @return string Hostname in lowercase
+     */
     abstract protected function getPrimaryDomain() : string;
 
+    /**
+     * @return array List of hostnames in lowercase
+     */
     abstract protected function getDomainList() : array;
 }
\ No newline at end of file
diff --git a/tests/Services/MultiDomainTest.php b/tests/Services/MultiDomainTest.php
index 3da37ad..505cb96 100644
--- a/tests/Services/MultiDomainTest.php
+++ b/tests/Services/MultiDomainTest.php
@@ -23,7 +23,8 @@ class MultiDomainTest extends \PHPUnit_Framework_TestCase
         return [
             [$this->getMultiDomainMock('foo.bar', ['foo.bar']), 'gmail.com', false],
             [$this->getMultiDomainMock('foo.bar', ['foo.bar', 'gmail.com']), 'gmail.com', true],
-            [$this->getMultiDomainMock('Foo.Bar', ['foo.bar', 'gmail.com']), 'gmail.com', true],
+            [$this->getMultiDomainMock('foo.bar', ['foo.bar', 'gmail.com']), 'GMAIL.COM', true],
+            [$this->getMultiDomainMock('foo.bar', ['foo.bar', 'gmail.com'], true), 'GMAIL.COM', true],
         ];
     }