diff --git a/book.php b/book.php
index 9e34104..cf1cbe9 100644
--- a/book.php
+++ b/book.php
@@ -146,7 +146,7 @@ class Book extends Base {
         }
         if (preg_match ("/<\/(div|p|a)>/", $this->comment))
         {
-            return $addition . preg_replace ("<(br|hr)>", "$1 /", $this->comment);
+            return $addition . preg_replace ("/<(br|hr)>/", "<$1 />", $this->comment);
         }
         else
         {