diff --git a/Michelf/Markdown.php b/Michelf/Markdown.php
index 43b3c79..9cf4c77 100644
--- a/Michelf/Markdown.php
+++ b/Michelf/Markdown.php
@@ -354,7 +354,7 @@ class Markdown implements MarkdownInterface {
 		$block_tags_b_re = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|address|'.
 						   'script|noscript|style|form|fieldset|iframe|math|svg|'.
 						   'article|section|nav|aside|hgroup|header|footer|'.
-						   'figure';
+						   'figure|details|summary';
 
 		// Regular expression for the content of a block tag.
 		$nested_tags_level = 4;
diff --git a/Michelf/MarkdownExtra.php b/Michelf/MarkdownExtra.php
index cf5b788..462adab 100644
--- a/Michelf/MarkdownExtra.php
+++ b/Michelf/MarkdownExtra.php
@@ -345,7 +345,7 @@ class MarkdownExtra extends \Michelf\Markdown {
 	 * Tags that are always treated as block tags
 	 * @var string
 	 */
-	protected $block_tags_re = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|address|form|fieldset|iframe|hr|legend|article|section|nav|aside|hgroup|header|footer|figcaption|figure';
+	protected $block_tags_re = 'p|div|h[1-6]|blockquote|pre|table|dl|ol|ul|address|form|fieldset|iframe|hr|legend|article|section|nav|aside|hgroup|header|footer|figcaption|figure|details|summary';
 
 	/**
 	 * Tags treated as block tags only if the opening tag is alone on its line