diff --git a/common/framework/filters/HTMLFilter.php b/common/framework/filters/HTMLFilter.php
index 8738c28fc..db2fb37e0 100644
--- a/common/framework/filters/HTMLFilter.php
+++ b/common/framework/filters/HTMLFilter.php
@@ -255,6 +255,8 @@ class HTMLFilter
 		$def->addElement('section', 'Block', 'Flow', 'Common');
 		$def->addElement('article', 'Block', 'Flow', 'Common');
 		$def->addElement('aside', 'Block', 'Flow', 'Common');
+		$def->addElement('details', 'Block', 'Flow', 'Common');
+		$def->addElement('summary', 'Block', 'Flow', 'Common');
 
 		// Add various inline tags.
 		$def->addElement('s', 'Inline', 'Inline', 'Common');
@@ -313,6 +315,7 @@ class HTMLFilter
 		));
 
 		// Support additional properties.
+		$def->addAttribute('details', 'open', 'Bool');
 		$def->addAttribute('i', 'aria-hidden', 'Text');
 		$def->addAttribute('img', 'srcset', 'Text');
 		$def->addAttribute('img', 'data-file-srl', 'Number');
diff --git a/tests/unit/framework/filters/HTMLFilterTest.php b/tests/unit/framework/filters/HTMLFilterTest.php
index 15b5629ae..edb539f59 100644
--- a/tests/unit/framework/filters/HTMLFilterTest.php
+++ b/tests/unit/framework/filters/HTMLFilterTest.php
@@ -83,6 +83,10 @@ class HTMLFilterTest extends \Codeception\TestCase\Test
 		$source = '<div contenteditable="true"><div contenteditable="false"><p contenteditable="false"></p></div></div>';
 		$target = '<div><div contenteditable="false"><p contenteditable="false"></p></div></div>';
 		$this->assertEquals($target, Rhymix\Framework\Filters\HTMLFilter::clean($source));
+
+		$source = '<details open><summary>Summary</summary><div>Content</div><p>Paragraph</p></details>';
+		$target = '<details open=""><summary>Summary</summary><div>Content</div><p>Paragraph</p></details>';
+		$this->assertEquals($target, Rhymix\Framework\Filters\HTMLFilter::clean($source));
 	}
 
 	public function testHTMLFilterCSS3()