diff --git a/common/framework/filters/mediafilter.php b/common/framework/filters/mediafilter.php
index 49080cdfe..380d085e1 100644
--- a/common/framework/filters/mediafilter.php
+++ b/common/framework/filters/mediafilter.php
@@ -79,7 +79,7 @@ class MediaFilter
 	 */
 	public static function formatPrefix($prefix)
 	{
-		$prefix = preg_match('@^(https?:)?//(.*)$@i', $prefix, $matches) ? $matches[2] : $prefix;
+		$prefix = preg_match('@^(?:https?:)?//(.*)$@i', $prefix, $matches) ? $matches[1] : $prefix;
 		if (strpos($prefix, '/') === false)
 		{
 			$prefix .= '/';
@@ -117,7 +117,7 @@ class MediaFilter
 		{
 			$result[] = str_replace('\*\.', '[a-z0-9-]+\.', preg_quote($domain, '%'));
 		}
-		return '%^(https?:)?//(' . implode('|', $result) . ')%';
+		return '%^(?:https?:)?//(' . implode('|', $result) . ')%';
 	}
 	
 	/**
@@ -150,7 +150,7 @@ class MediaFilter
 		{
 			$result[] = str_replace('\*\.', '[a-z0-9-]+\.', preg_quote($domain, '%'));
 		}
-		return '%^(https?:)?//(' . implode('|', $result) . ')%';
+		return '%^(?:https?:)?//(' . implode('|', $result) . ')%';
 	}
 	
 	/**
diff --git a/tests/unit/framework/filters/MediaFilterTest.php b/tests/unit/framework/filters/MediaFilterTest.php
index 1e865a240..3b10ca4e9 100644
--- a/tests/unit/framework/filters/MediaFilterTest.php
+++ b/tests/unit/framework/filters/MediaFilterTest.php
@@ -16,6 +16,10 @@ class MediaFilterTest extends \Codeception\TestCase\Test
 		$this->assertTrue(Rhymix\Framework\Filters\MediaFilter::matchIframeWhitelist('https://www.youtube.com/v'));
 		$this->assertFalse(Rhymix\Framework\Filters\MediaFilter::matchIframeWhitelist('http://www-youtube.com/v'));
 		
+		// Match protocol-relative URLs.
+		$this->assertTrue(Rhymix\Framework\Filters\MediaFilter::matchIframeWhitelist('//www.youtube.com/v'));
+		$this->assertFalse(Rhymix\Framework\Filters\MediaFilter::matchIframeWhitelist('//www-youtube.com/v'));
+		
 		// object whitelist as array.
 		$this->assertTrue(in_array('www.youtube.com/', Rhymix\Framework\Filters\MediaFilter::getObjectWhitelist()));
 		$this->assertFalse(in_array('random-website.com/', Rhymix\Framework\Filters\MediaFilter::getObjectWhitelist()));
@@ -27,6 +31,10 @@ class MediaFilterTest extends \Codeception\TestCase\Test
 		// Match individual URL against object whitelist.
 		$this->assertTrue(Rhymix\Framework\Filters\MediaFilter::matchObjectWhitelist('https://www.youtube.com/v'));
 		$this->assertFalse(Rhymix\Framework\Filters\MediaFilter::matchObjectWhitelist('http://www-youtube.com/v'));
+		
+		// Match protocol-relative URLs.
+		$this->assertTrue(Rhymix\Framework\Filters\MediaFilter::matchObjectWhitelist('//www.youtube.com/v'));
+		$this->assertFalse(Rhymix\Framework\Filters\MediaFilter::matchObjectWhitelist('//www-youtube.com/v'));
 	}
 	
 	public function testAddPrefix()