diff --git a/src/Components/Blocks/FencedCode.php b/src/Components/Blocks/FencedCode.php
index 87d3bb4..a93dd1b 100644
--- a/src/Components/Blocks/FencedCode.php
+++ b/src/Components/Blocks/FencedCode.php
@@ -118,7 +118,23 @@ final class FencedCode implements ContinuableBlock
      */
     public function stateRenderable()
     {
-        $infostring = $this->infostring();
+        /**
+         * https://www.w3.org/TR/2011/WD-html5-20110525/elements.html#classes
+         * Every HTML element may have a class attribute specified.
+         * The attribute, if specified, must have a value that is a set
+         * of space-separated tokens representing the various classes
+         * that the element belongs to.
+         * [...]
+         * The space characters, for the purposes of this specification,
+         * are U+0020 SPACE, U+0009 CHARACTER TABULATION (tab),
+         * U+000A LINE FEED (LF), U+000C FORM FEED (FF), and
+         * U+000D CARRIAGE RETURN (CR).
+         */
+        $infostring = \substr(
+            $this->infostring(),
+            0,
+            \strcspn($this->infostring(), " \t\n\f\r")
+        );
 
         return new Element('pre', [], [new Element(
             'code',
diff --git a/tests/data/fenced_code_block.html b/tests/data/fenced_code_block.html
index fd91256..2060e44 100644
--- a/tests/data/fenced_code_block.html
+++ b/tests/data/fenced_code_block.html
@@ -22,4 +22,7 @@ still a fenced code block
 
 
 bar
+</code></pre>
+<pre><code class="language-php">&lt;?php
+echo &quot;Hello World&quot;;
 </code></pre>
\ No newline at end of file
diff --git a/tests/data/fenced_code_block.md b/tests/data/fenced_code_block.md
index 3e4155a..81ca2ba 100644
--- a/tests/data/fenced_code_block.md
+++ b/tests/data/fenced_code_block.md
@@ -35,4 +35,9 @@ foo
 
 
 bar
+```
+
+```php some-class
+<?php
+echo "Hello World";
 ```
\ No newline at end of file