diff --git a/library/HTMLPurifier.php b/library/HTMLPurifier.php
index b74a2780..7168f039 100644
--- a/library/HTMLPurifier.php
+++ b/library/HTMLPurifier.php
@@ -39,9 +39,6 @@
     Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-// constants are slow, but we'll make one exception
-define('HTMLPURIFIER_PREFIX', dirname(__FILE__));
-
 /**
  * Facade that coordinates HTML Purifier's subsystems in order to purify HTML.
  * 
diff --git a/library/HTMLPurifier/Bootstrap.php b/library/HTMLPurifier/Bootstrap.php
index fa5e7ce2..83ee4845 100644
--- a/library/HTMLPurifier/Bootstrap.php
+++ b/library/HTMLPurifier/Bootstrap.php
@@ -1,5 +1,8 @@
 <?php
 
+// constants are slow, but we'll make one exception
+define('HTMLPURIFIER_PREFIX', dirname(__FILE__));
+
 /**
  * Bootstrap class that contains meta-functionality for HTML Purifier such as
  * the autoload function.