diff --git a/library/HTMLPurifier/HTML5Config.php b/library/HTMLPurifier/HTML5Config.php
index 6c55240..c518b83 100644
--- a/library/HTMLPurifier/HTML5Config.php
+++ b/library/HTMLPurifier/HTML5Config.php
@@ -29,9 +29,15 @@ public static function create($config = null, HTMLPurifier_ConfigSchema $schema
             }
         }
 
-        $def = $configObj->getHTMLDefinition(true); // this finalizes config
+        // Prevent auto-finalization of config when retrieving HTML definition
+        $autoFinalize = $configObj->autoFinalize;
+        $configObj->autoFinalize = false;
+
+        $def = $configObj->getHTMLDefinition(true);
         HTMLPurifier_HTML5Definition::setup($def);
 
+        $configObj->autoFinalize = $autoFinalize;
+
         return $configObj;
     }
 
diff --git a/tests/HTMLPurifier/HTML5ConfigTest.php b/tests/HTMLPurifier/HTML5ConfigTest.php
index 5239493..6735a14 100644
--- a/tests/HTMLPurifier/HTML5ConfigTest.php
+++ b/tests/HTMLPurifier/HTML5ConfigTest.php
@@ -15,5 +15,10 @@ public function testCreate()
         ));
         $this->assertInstanceOf('HTMLPurifier_Config', $config3);
         $this->assertEquals('iso-8859-1', $config3->get('Core.Encoding'));
+
+        $config4 = HTMLPurifier_HTML5Config::create();
+        $config4->set('Core.Encoding', 'iso-8859-1');
+        $this->assertInstanceOf('HTMLPurifier_Config', $config4);
+        $this->assertEquals('iso-8859-1', $config4->get('Core.Encoding'));
     }
 }