diff --git a/phpBB/phpbb/textformatter/s9e/utils.php b/phpBB/phpbb/textformatter/s9e/utils.php
index 40479b3423..b317fe4a8d 100644
--- a/phpBB/phpbb/textformatter/s9e/utils.php
+++ b/phpBB/phpbb/textformatter/s9e/utils.php
@@ -70,6 +70,12 @@ class utils implements \phpbb\textformatter\utils_interface
 			$quote .= '=' . $this->format_attribute_value($attributes['author']);
 			unset($attributes['author']);
 		}
+
+		if (isset($attributes['user_id']) && $attributes['user_id'] == ANONYMOUS)
+		{
+			unset($attributes['user_id']);
+		}
+
 		ksort($attributes);
 		foreach ($attributes as $name => $value)
 		{
diff --git a/tests/text_formatter/s9e/utils_test.php b/tests/text_formatter/s9e/utils_test.php
index 1c03783792..dade259790 100644
--- a/tests/text_formatter/s9e/utils_test.php
+++ b/tests/text_formatter/s9e/utils_test.php
@@ -175,6 +175,15 @@ class phpbb_textformatter_s9e_utils_test extends phpbb_test_case
 				),
 				'[quote=user post_id=123 url=http://example.org]...[/quote]',
 			),
+			array(
+				'...',
+				array(
+					'author'  => 'user',
+					'post_id' => 123,
+					'user_id' => ANONYMOUS
+				),
+				'[quote=user post_id=123]...[/quote]',
+			),
 			array(
 				'...',
 				array('author'  => ' '),