diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index 379422b819..61a156ae65 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -36,7 +36,7 @@ function gen_rand_string($num_chars = 8)
 	$output = '';
 	for ($i = 0; $i < $num_chars; $i++)
 	{
-		$rand = random_int(0, $size-1);
+		$rand = random_int(0, $size - 1);
 		$output .= $range[$rand];
 	}
 
diff --git a/phpBB/includes/message_parser.php b/phpBB/includes/message_parser.php
index e82b2168b4..337b6ccab8 100644
--- a/phpBB/includes/message_parser.php
+++ b/phpBB/includes/message_parser.php
@@ -1056,7 +1056,8 @@ class parse_message extends bbcode_firstpass
 	function __construct($message = '')
 	{
 		// Init BBCode UID
-		$this->bbcode_uid = substr(base_convert(unique_id(), 16, 36), 0, BBCODE_UID_LEN);
+		$unique_id = preg_replace('/[^0-9a-f]/', '', unique_id());
+		$this->bbcode_uid = substr(base_convert($unique_id, 16, 36), 0, BBCODE_UID_LEN);
 		$this->message = $message;
 	}