diff --git a/NEWS b/NEWS
index 68b3ad6e..a83e1b5e 100644
--- a/NEWS
+++ b/NEWS
@@ -29,6 +29,8 @@ NEWS ( CHANGELOG and HISTORY )                                     HTMLPurifier
   to migrate an %HTML.AllowedAttributes directives to this syntax too.
 ! Allow index to be false for config from form creation
 ! Added HTMLPurifier::VERSION constant
+! Commas, not dashes, used for serializer IDs. This change is forwards-compatible
+  and allows for version numbers like "3.1.0-dev".
 - InterchangeBuilder now alphabetizes its lists
 - Validation error in configdoc output fixed
 - Iconv and other encoding errors muted even with custom error handlers that
diff --git a/TODO b/TODO
index 9af74f95..bfd5a269 100644
--- a/TODO
+++ b/TODO
@@ -11,6 +11,9 @@ If no interest is expressed for a feature that may require a considerable
 amount of effort to implement, it may get endlessly delayed. Do not be
 afraid to cast your vote for the next feature to be implemented!
 
+ - Get PH5P working with the latest versions of DOM, which have much more
+   stringent error checking procedures. Maybe convert straight to tokens.
+
 FUTURE VERSIONS
 ---------------
 
diff --git a/configdoc/usage.xml b/configdoc/usage.xml
index 800180cc..19e2f621 100644
--- a/configdoc/usage.xml
+++ b/configdoc/usage.xml
@@ -131,12 +131,12 @@
  </directive>
  <directive id="HTML.ForbiddenElements">
   <file name="HTMLPurifier/HTMLDefinition.php">
-   <line>326</line>
+   <line>328</line>
   </file>
  </directive>
  <directive id="HTML.ForbiddenAttributes">
   <file name="HTMLPurifier/HTMLDefinition.php">
-   <line>327</line>
+   <line>329</line>
   </file>
  </directive>
  <directive id="HTML.Trusted">
diff --git a/library/HTMLPurifier/Config.php b/library/HTMLPurifier/Config.php
index bb854849..616ca06f 100644
--- a/library/HTMLPurifier/Config.php
+++ b/library/HTMLPurifier/Config.php
@@ -72,7 +72,7 @@ class HTMLPurifier_Config
      * @param $definition HTMLPurifier_ConfigSchema that defines what directives
      *                    are allowed.
      */
-    public function __construct(&$definition) {
+    public function __construct($definition) {
         $this->conf = $definition->defaults; // set up, copy in defaults
         $this->def  = $definition; // keep a copy around for checking
         $this->parser = new HTMLPurifier_VarParser_Flexible();
diff --git a/library/HTMLPurifier/DefinitionCache.php b/library/HTMLPurifier/DefinitionCache.php
index 020b01c3..f81af0c5 100644
--- a/library/HTMLPurifier/DefinitionCache.php
+++ b/library/HTMLPurifier/DefinitionCache.php
@@ -26,8 +26,8 @@ abstract class HTMLPurifier_DefinitionCache
      * @param Instance of HTMLPurifier_Config
      */
     public function generateKey($config) {
-        return $config->version . '-' . // possibly replace with function calls
-               $config->getBatchSerial($this->type) . '-' .
+        return $config->version . ',' . // possibly replace with function calls
+               $config->getBatchSerial($this->type) . ',' .
                $config->get($this->type, 'DefinitionRev');
     }
     
@@ -38,8 +38,8 @@ abstract class HTMLPurifier_DefinitionCache
      * @param $config Instance of HTMLPurifier_Config to test against
      */
     public function isOld($key, $config) {
-        if (substr_count($key, '-') < 2) return true;
-        list($version, $hash, $revision) = explode('-', $key, 3);
+        if (substr_count($key, ',') < 2) return true;
+        list($version, $hash, $revision) = explode(',', $key, 3);
         $compare = version_compare($version, $config->version);
         // version mismatch, is always old
         if ($compare != 0) return true;
diff --git a/library/HTMLPurifier/DefinitionCacheFactory.php b/library/HTMLPurifier/DefinitionCacheFactory.php
index 2d9aeca3..fca1b6c4 100644
--- a/library/HTMLPurifier/DefinitionCacheFactory.php
+++ b/library/HTMLPurifier/DefinitionCacheFactory.php
@@ -48,8 +48,7 @@ class HTMLPurifier_DefinitionCacheFactory
     public function create($type, $config) {
         $method = $config->get('Cache', 'DefinitionImpl');
         if ($method === null) {
-            $null = new HTMLPurifier_DefinitionCache_Null($type);
-            return $null;
+            return new HTMLPurifier_DefinitionCache_Null($type);
         }
         if (!empty($this->caches[$method][$type])) {
             return $this->caches[$method][$type];
diff --git a/tests/HTMLPurifier/DefinitionCache/SerializerTest.php b/tests/HTMLPurifier/DefinitionCache/SerializerTest.php
index 446bfc85..41765f7f 100644
--- a/tests/HTMLPurifier/DefinitionCache/SerializerTest.php
+++ b/tests/HTMLPurifier/DefinitionCache/SerializerTest.php
@@ -11,7 +11,7 @@ class HTMLPurifier_DefinitionCache_SerializerTest extends HTMLPurifier_Definitio
         $config->setReturnValue('get', 2, array('Test', 'DefinitionRev'));
         $config->version = '1.0.0';
         
-        $config_md5   = '1.0.0-serial-2';
+        $config_md5   = '1.0.0,serial,2';
         
         $file = realpath(
             $rel_file = HTMLPURIFIER_PREFIX . '/HTMLPurifier/DefinitionCache/Serializer/Test/' .
@@ -186,9 +186,9 @@ class HTMLPurifier_DefinitionCache_SerializerTest extends HTMLPurifier_Definitio
         
         $def_original = $this->generateDefinition();
         $cache->add($def_original, $config);
-        $this->assertFileExist($dir . '/Test/1.0.0-serial-1.ser');
+        $this->assertFileExist($dir . '/Test/1.0.0,serial,1.ser');
         
-        unlink($dir . '/Test/1.0.0-serial-1.ser');
+        unlink($dir . '/Test/1.0.0,serial,1.ser');
         rmdir( $dir . '/Test');
         
     }
diff --git a/tests/HTMLPurifier/DefinitionCacheTest.php b/tests/HTMLPurifier/DefinitionCacheTest.php
index 58ba8867..8e6d4378 100644
--- a/tests/HTMLPurifier/DefinitionCacheTest.php
+++ b/tests/HTMLPurifier/DefinitionCacheTest.php
@@ -13,16 +13,17 @@ class HTMLPurifier_DefinitionCacheTest extends HTMLPurifier_Harness
         $config->setReturnValue('get', 10, array('Test', 'DefinitionRev'));
         $config->setReturnValue('getBatchSerial', 'hash', array('Test'));
         
-        $this->assertIdentical($cache->isOld('1.0.0-hash-10', $config), false);
-        $this->assertIdentical($cache->isOld('1.5.0-hash-1', $config), true);
+        $this->assertIdentical($cache->isOld('1.0.0,hash,10', $config), false);
+        $this->assertIdentical($cache->isOld('1.5.0,hash,1', $config), true);
         
-        $this->assertIdentical($cache->isOld('0.9.0-hash-1', $config), true);
-        $this->assertIdentical($cache->isOld('1.0.0-hash-1', $config), true);
-        $this->assertIdentical($cache->isOld('1.0.0beta-hash-11', $config), true);
+        $this->assertIdentical($cache->isOld('0.9.0,hash,1', $config), true);
+        $this->assertIdentical($cache->isOld('1.0.0,hash,1', $config), true);
+        $this->assertIdentical($cache->isOld('1.0.0beta,hash,11', $config), true);
         
-        $this->assertIdentical($cache->isOld('0.9.0-hash2-1', $config), true);
-        $this->assertIdentical($cache->isOld('1.0.0-hash2-1', $config), false); // if hash is different, don't touch!
-        $this->assertIdentical($cache->isOld('1.0.0beta-hash2-11', $config), true);
+        $this->assertIdentical($cache->isOld('0.9.0,hash2,1', $config), true);
+        $this->assertIdentical($cache->isOld('1.0.0,hash2,1', $config), false); // if hash is different, don't touch!
+        $this->assertIdentical($cache->isOld('1.0.0beta,hash2,11', $config), true);
+        $this->assertIdentical($cache->isOld('1.0.0-dev,hash2,11', $config), true);
         
     }
     
diff --git a/tests/HTMLPurifier/HTMLDefinitionTest.php b/tests/HTMLPurifier/HTMLDefinitionTest.php
index 5b4f5e77..35048ab0 100644
--- a/tests/HTMLPurifier/HTMLDefinitionTest.php
+++ b/tests/HTMLPurifier/HTMLDefinitionTest.php
@@ -3,6 +3,13 @@
 class HTMLPurifier_HTMLDefinitionTest extends HTMLPurifier_Harness
 {
     
+    function expectError($error = false, $message = '%s') {
+        // Because we're testing a definition, it's vital that the cache
+        // is turned off for tests that expect errors.
+        $this->config->set('Cache', 'DefinitionImpl', null);
+        parent::expectError($error);
+    }
+    
     function test_parseTinyMCEAllowedList() {
         
         $def = new HTMLPurifier_HTMLDefinition();
@@ -85,21 +92,18 @@ a[href|title]
     }
     
     function test_AllowedElements_invalidElement() {
-        $this->config->set('Cache', 'DefinitionImpl', null); // Necessary to ensure error is thrown
         $this->config->set('HTML', 'AllowedElements', 'obviously_invalid,p');
         $this->expectError(new PatternExpectation("/Element 'obviously_invalid' is not supported/"));
         $this->assertPurification_AllowedElements_p();
     }
     
     function test_AllowedElements_invalidElement_xssAttempt() {
-        $this->config->set('Cache', 'DefinitionImpl', null);
         $this->config->set('HTML', 'AllowedElements', '<script>,p');
         $this->expectError(new PatternExpectation("/Element '&lt;script&gt;' is not supported/"));
         $this->assertPurification_AllowedElements_p();
     }
     
     function test_AllowedElements_multipleInvalidElements() {
-        $this->config->set('Cache', 'DefinitionImpl', null);
         $this->config->set('HTML', 'AllowedElements', 'dr-wiggles,dr-pepper,p');
         $this->expectError(new PatternExpectation("/Element 'dr-wiggles' is not supported/"));
         $this->expectError(new PatternExpectation("/Element 'dr-pepper' is not supported/"));
@@ -153,21 +157,18 @@ a[href|title]
     }
     
     function test_AllowedAttributes_local_invalidAttribute() {
-        $this->config->set('Cache', 'DefinitionImpl', null);
         $this->config->set('HTML', 'AllowedAttributes', array('p@style', 'p@<foo>'));
         $this->expectError(new PatternExpectation("/Attribute '&lt;foo&gt;' in element 'p' not supported/"));
         $this->assertPurification_AllowedAttributes_local_p_style();
     }
     
     function test_AllowedAttributes_global_invalidAttribute() {
-        $this->config->set('Cache', 'DefinitionImpl', null);
         $this->config->set('HTML', 'AllowedAttributes', array('style', '<foo>'));
         $this->expectError(new PatternExpectation("/Global attribute '&lt;foo&gt;' is not supported in any elements/"));
         $this->assertPurification_AllowedAttributes_global_style();
     }
     
     function test_AllowedAttributes_local_invalidAttributeDueToMissingElement() {
-        $this->config->set('Cache', 'DefinitionImpl', null);
         $this->config->set('HTML', 'AllowedAttributes', 'p.style,foo.style');
         $this->expectError(new PatternExpectation("/Cannot allow attribute 'style' if element 'foo' is not allowed\/supported/"));
         $this->assertPurification_AllowedAttributes_local_p_style();
@@ -208,7 +209,6 @@ a[href|title]
     }
     
     function test_ForbiddenAttributes_incorrectSyntax() {
-        $this->config->set('Cache', 'DefinitionImpl', null);
         $this->config->set('HTML', 'ForbiddenAttributes', 'b.style');
         $this->expectError("Error with b.style: tag.attr syntax not supported for HTML.ForbiddenAttributes; use tag@attr instead");
         $this->assertPurification('<b style="float:left;">Test</b>');