diff --git a/library/HTMLPurifier.php b/library/HTMLPurifier.php
index d06af2a5..64544dcf 100644
--- a/library/HTMLPurifier.php
+++ b/library/HTMLPurifier.php
@@ -159,8 +159,7 @@ class HTMLPurifier
         
         // setup id_accumulator context, necessary due to the fact that
         // AttrValidator can be called from many places
-        $id_accumulator = new HTMLPurifier_IDAccumulator();
-        $id_accumulator->load($config->get('Attr', 'IDBlacklist'));
+        $id_accumulator = HTMLPurifier_IDAccumulator::build($config, $context);
         $context->register('IDAccumulator', $id_accumulator);
         
         $html = HTMLPurifier_Encoder::convertToUTF8($html, $config, $context);
diff --git a/library/HTMLPurifier/AttrValidator.php b/library/HTMLPurifier/AttrValidator.php
index f02bd208..a471b093 100644
--- a/library/HTMLPurifier/AttrValidator.php
+++ b/library/HTMLPurifier/AttrValidator.php
@@ -23,6 +23,13 @@ class HTMLPurifier_AttrValidator
         $definition = $config->getHTMLDefinition();
         $e =& $context->get('ErrorCollector', true);
         
+        // initialize IDAccumulator if necessary
+        $ok =& $context->get('IDAccumulator', true);
+        if (!$ok) {
+            $id_accumulator = HTMLPurifier_IDAccumulator::build($config, $context);
+            $context->register('IDAccumulator', $id_accumulator);
+        }
+        
         // initialize CurrentToken if necessary
         $current_token =& $context->get('CurrentToken', true);
         if (!$current_token) $context->register('CurrentToken', $token);
diff --git a/library/HTMLPurifier/IDAccumulator.php b/library/HTMLPurifier/IDAccumulator.php
index 525c9aa0..60715afc 100644
--- a/library/HTMLPurifier/IDAccumulator.php
+++ b/library/HTMLPurifier/IDAccumulator.php
@@ -1,11 +1,15 @@
 <?php
 
+HTMLPurifier_ConfigSchema::define(
+    'Attr', 'IDBlacklist', array(), 'list',
+    'Array of IDs not allowed in the document.'
+);
+
 /**
  * Component of HTMLPurifier_AttrContext that accumulates IDs to prevent dupes
  * @note In Slashdot-speak, dupe means duplicate.
- * @note This class does not accept $config or $context, thus, it is the
- *       burden of the callee to register the appropriate errors or
- *       configuration.
+ * @note The default constructor does not accept $config or $context objects:
+ *       use must use the static build() factory method to perform initialization.
  */
 class HTMLPurifier_IDAccumulator
 {
@@ -16,6 +20,19 @@ class HTMLPurifier_IDAccumulator
      */
     var $ids = array();
     
+    /**
+     * Builds an IDAccumulator, also initializing the default blacklist
+     * @param $config Instance of HTMLPurifier_Config
+     * @param $context Instance of HTMLPurifier_Context
+     * @return Fully initialized HTMLPurifier_IDAccumulator
+     * @static
+     */
+    function build($config, &$context) {
+        $id_accumulator = new HTMLPurifier_IDAccumulator();
+        $id_accumulator->load($config->get('Attr', 'IDBlacklist'));
+        return $id_accumulator;
+    }
+    
     /**
      * Add an ID to the lookup table.
      * @param $id ID to be added.
diff --git a/library/HTMLPurifier/Strategy/ValidateAttributes.php b/library/HTMLPurifier/Strategy/ValidateAttributes.php
index 87772406..6debcc33 100644
--- a/library/HTMLPurifier/Strategy/ValidateAttributes.php
+++ b/library/HTMLPurifier/Strategy/ValidateAttributes.php
@@ -6,10 +6,6 @@ require_once 'HTMLPurifier/IDAccumulator.php';
 
 require_once 'HTMLPurifier/AttrValidator.php';
 
-HTMLPurifier_ConfigSchema::define(
-    'Attr', 'IDBlacklist', array(), 'list',
-    'Array of IDs not allowed in the document.');
-
 /**
  * Validate all attributes in the tokens.
  */
diff --git a/tests/HTMLPurifier/IDAccumulatorTest.php b/tests/HTMLPurifier/IDAccumulatorTest.php
index 006d689c..c6249eca 100644
--- a/tests/HTMLPurifier/IDAccumulatorTest.php
+++ b/tests/HTMLPurifier/IDAccumulatorTest.php
@@ -30,5 +30,11 @@ class HTMLPurifier_IDAccumulatorTest extends HTMLPurifier_Harness
         
     }
     
+    function testBuild() {
+        $this->config->set('Attr', 'IDBlacklist', array('foo'));
+        $accumulator = HTMLPurifier_IDAccumulator::build($this->config, $this->context);
+        $this->assertTrue( isset($accumulator->ids['foo']) );
+    }
+    
 }
 
diff --git a/tests/HTMLPurifierTest.php b/tests/HTMLPurifierTest.php
index 3ad307bb..6a221b24 100644
--- a/tests/HTMLPurifierTest.php
+++ b/tests/HTMLPurifierTest.php
@@ -94,6 +94,7 @@ class HTMLPurifierTest extends HTMLPurifier_Harness
         
         $this->purifier = new HTMLPurifier(array('HTML.EnableAttrID' => true));
         $this->assertPurification('<span id="moon">foobar</span>');
+        $this->assertPurification('<img id="folly" src="folly.png" alt="Omigosh!" />');
         
     }