diff --git a/NEWS b/NEWS
index 7d1e8a94..65f8dd5b 100644
--- a/NEWS
+++ b/NEWS
@@ -14,6 +14,7 @@ NEWS ( CHANGELOG and HISTORY )                                     HTMLPurifier
   to http.  Reported by Neike Taika-Tessaro.
 - Color keywords are now case insensitive.  Thanks Yzmir Ramirez
   <yramirez-htmlpurifier@adicio.com> for reporting.
+- Explicitly initialize anonModule variable to null.
 
 4.3.0, released 2011-03-27
 # Fixed broken caching of customized raw definitions, but requires an
diff --git a/library/HTMLPurifier/HTMLDefinition.php b/library/HTMLPurifier/HTMLDefinition.php
index 33bb38ac..b079d44c 100644
--- a/library/HTMLPurifier/HTMLDefinition.php
+++ b/library/HTMLPurifier/HTMLDefinition.php
@@ -147,7 +147,7 @@ class HTMLPurifier_HTMLDefinition extends HTMLPurifier_Definition
         return $this->_anonModule;
     }
 
-    private $_anonModule;
+    private $_anonModule = null;
 
 
     // PUBLIC BUT INTERNAL VARIABLES --------------------------------------