diff --git a/library/HTMLPurifier/IDAccumulator.php b/library/HTMLPurifier/IDAccumulator.php
new file mode 100644
index 00000000..a90f93f7
--- /dev/null
+++ b/library/HTMLPurifier/IDAccumulator.php
@@ -0,0 +1,27 @@
+<?php
+
+class HTMLPurifier_IDAccumulator
+{
+    
+    var $ids = array();
+    
+    function &instance() {
+        static $instance = null;
+        if (empty($instance)) {
+            $instance = new HTMLPurifier_IDAccumulator();
+        }
+        return $instance;
+    }
+    
+    function add($id) {
+        if (isset($this->ids[$id])) return false;
+        return $this->ids[$id] = true;
+    }
+    
+    function reset() {
+        $this->ids = array();
+    }
+    
+}
+
+?>
\ No newline at end of file
diff --git a/tests/HTMLPurifier/IDAccumulatorTest.php b/tests/HTMLPurifier/IDAccumulatorTest.php
new file mode 100644
index 00000000..377e973e
--- /dev/null
+++ b/tests/HTMLPurifier/IDAccumulatorTest.php
@@ -0,0 +1,26 @@
+<?php
+
+require_once 'HTMLPurifier/IDAccumulator.php';
+
+class HTMLPurifier_IDAccumulatorTest extends UnitTestCase
+{
+    
+    function test() {
+        
+        // initialize the accumulator
+        $accumulator = HTMLPurifier_IDAccumulator::instance();
+        $accumulator->reset();
+        
+        $this->assertTrue( $accumulator->add('id1'));
+        $this->assertTrue( $accumulator->add('id2'));
+        $this->assertFalse($accumulator->add('id1')); // repeated id
+        $accumulator->reset();
+        
+        $this->assertTrue( $accumulator->add('id2')); // test reset
+        $accumulator->reset();
+        
+    }
+    
+}
+
+?>
\ No newline at end of file
diff --git a/tests/index.php b/tests/index.php
index 5cb61927..05ec1b4a 100644
--- a/tests/index.php
+++ b/tests/index.php
@@ -33,6 +33,7 @@ $test->addTestFile('HTMLPurifier/Strategy/FixNestingTest.php');
 $test->addTestFile('HTMLPurifier/Strategy/CompositeTest.php');
 $test->addTestFile('HTMLPurifier/Strategy/CoreTest.php');
 $test->addTestFile('HTMLPurifier/AttrDef/EnumTest.php');
+$test->addTestFile('HTMLPurifier/IDAccumulatorTest.php');
 
 $test->run( new HtmlReporter() );