diff --git a/wp-admin/edit-form-advanced.php b/wp-admin/edit-form-advanced.php
index 6fb9b2185..cacf951f3 100644
--- a/wp-admin/edit-form-advanced.php
+++ b/wp-admin/edit-form-advanced.php
@@ -104,9 +104,6 @@ foreach ( get_object_taxonomies($post_type) as $tax_name ) {
 		add_meta_box('tagsdiv-' . $tax_name, $label, 'post_tags_meta_box', $post_type, 'side', 'core');
 	else
 		add_meta_box($tax_name . 'div', $label, 'post_categories_meta_box', $post_type, 'side', 'core', array( 'taxonomy' => $tax_name ));
-
-	// register callback handling for metabox
- 	add_filter('wp_ajax_add-' . $tax_name, '_wp_ajax_add_hierarchical_term');
 }
 
 if ( post_type_supports($post_type, 'page-attributes') )
diff --git a/wp-includes/taxonomy.php b/wp-includes/taxonomy.php
index 7e24ba52b..78b21779a 100644
--- a/wp-includes/taxonomy.php
+++ b/wp-includes/taxonomy.php
@@ -294,6 +294,9 @@ function register_taxonomy( $taxonomy, $object_type, $args = array() ) {
 	$args['name'] = $taxonomy;
 	$args['object_type'] = (array) $object_type;
 	$wp_taxonomies[$taxonomy] = (object) $args;
+
+	// register callback handling for metabox
+ 	add_filter('wp_ajax_add-'.$taxonomy, '_wp_ajax_add_hierarchical_term');
 }
 
 /**