diff --git a/library/HTMLPurifier/AttrDef/Number.php b/library/HTMLPurifier/AttrDef/Number.php
new file mode 100644
index 00000000..d596d136
--- /dev/null
+++ b/library/HTMLPurifier/AttrDef/Number.php
@@ -0,0 +1,45 @@
+<?php
+
+class HTMLPurifier_AttrDef_Number extends HTMLPurifier_AttrDef
+{
+    
+    function validate($number, $config, &$context) {
+        
+        $number = $this->parseCDATA($number);
+        
+        if ($number === '') return false;
+        
+        $sign = '';
+        switch ($number[0]) {
+            case '-':
+                $sign = '-';
+            case '+':
+                $number = substr($number, 1);
+        }
+        
+        if (ctype_digit($number)) {
+            $number = ltrim($number, '0');
+            return $number ? $sign . $number : '0';
+        }
+        if (!strpos($number, '.')) return false;
+        
+        list($left, $right) = explode('.', $number, 2);
+        
+        if (!ctype_digit($left)) return false;
+        $left = ltrim($left, '0');
+        
+        $right = rtrim($right, '0');
+        
+        if ($right === '') {
+            return $left ? $sign . $left : '0';
+        } elseif (!ctype_digit($right)) {
+            return false;
+        }
+        
+        return $sign . $left . '.' . $right;
+        
+    }
+    
+}
+
+?>
\ No newline at end of file
diff --git a/tests/HTMLPurifier/AttrDef/NumberTest.php b/tests/HTMLPurifier/AttrDef/NumberTest.php
new file mode 100644
index 00000000..4c6f3b13
--- /dev/null
+++ b/tests/HTMLPurifier/AttrDef/NumberTest.php
@@ -0,0 +1,31 @@
+<?php
+
+require_once 'HTMLPurifier/AttrDef/Number.php';
+
+class HTMLPurifier_AttrDef_NumberTest extends HTMLPurifier_AttrDefHarness
+{
+    
+    function test() {
+        
+        $this->def = new HTMLPurifier_AttrDef_Number();
+        
+        $this->assertDef('0');
+        $this->assertDef('34');
+        $this->assertDef('4.5');
+        $this->assertDef('-56.9');
+        
+        $this->assertDef('000', '0');
+        $this->assertDef(' 9', '9');
+        $this->assertDef('+5.0000', '5');
+        $this->assertDef('02.20', '2.2');
+        $this->assertDef('2.', '2');
+        
+        $this->assertDef('.', false);
+        $this->assertDef('asdf', false);
+        $this->assertDef('0.5.6', false);
+        
+    }
+    
+}
+
+?>
\ No newline at end of file
diff --git a/tests/index.php b/tests/index.php
index c035dd6a..c4f00230 100644
--- a/tests/index.php
+++ b/tests/index.php
@@ -67,6 +67,7 @@ $test_files[] = 'AttrDef/CSSTest.php';
 $test_files[] = 'AttrDef/CompositeTest.php';
 $test_files[] = 'AttrDef/ColorTest.php';
 $test_files[] = 'AttrDef/IntegerTest.php';
+$test_files[] = 'AttrDef/NumberTest.php';
 $test_files[] = 'IDAccumulatorTest.php';
 $test_files[] = 'TagTransformTest.php';
 $test_files[] = 'AttrTransform/LangTest.php';