diff --git a/opentools-update-checker.php b/opentools-update-checker.php
index c585fa866f16862278bd77bd788b7b7f1b63b77f..c14931614456e2b484161afbfcfce2f6feb19fdf 100644
--- a/opentools-update-checker.php
+++ b/opentools-update-checker.php
@@ -27,15 +27,15 @@ class OpenToolsPluginUpdateChecker extends PluginUpdateChecker_2_1 {
 	}
 	public function declareCredentials($credential_def) {
 		$this->credvars = $credential_def;
+		// Append the update credentials to the update server link
+		$this->addQueryArgFilter(array($this, 'appendQueryArgsCredentials'));
+		
 	}
 	
 	protected function installOTHooks() 
 	{
 		$this->ajaxurl = is_network_admin()?network_admin_url( 'admin-ajax.php' ): admin_url( 'admin-ajax.php' );
 		
-		// Append the update credentials to the update server link
-		$this->addQueryArgFilter(array($this, 'appendQueryArgsCredentials'));
-		
 		add_action('admin_print_scripts-plugins.php', array($this, 'addCredentialCheckScripts'));
 		add_action('admin_print_styles-plugins.php',  array($this, 'addCredentialCheckStyles'));
 
@@ -99,6 +99,7 @@ class OpenToolsPluginUpdateChecker extends PluginUpdateChecker_2_1 {
 	public function displayUpdateCredentialsLink($links, $pluginFile) {
 		$isRelevant = ($pluginFile == $this->pluginFile)
 		              || (!empty($this->muPluginFile) && $pluginFile == $this->muPluginFile);
+		$isRelevant = $isRelevant && !empty($this->credvars);
 
 		if ( $isRelevant && current_user_can('update_plugins') ) {
 			$credentials = $this->getCredentials($this->slug);
@@ -127,6 +128,7 @@ class OpenToolsPluginUpdateChecker extends PluginUpdateChecker_2_1 {
 			&& $_REQUEST['slug'] == $this->slug
 			&& current_user_can('update_plugins')
 			&& check_ajax_referer('otup_enter_update_credentials');
+		$showCredentials = $showCredentials && !empty($this->credvars);
 			
 		if ( $showCredentials && (is_network_admin() || !is_multisite() )) {
 			$slug = $this->slug;
@@ -179,7 +181,7 @@ class OpenToolsPluginUpdateChecker extends PluginUpdateChecker_2_1 {
 		$submitCredentials = $slug == $this->slug
 			&& current_user_can('update_plugins')
 			&& check_ajax_referer('otup_enter_update_credentials_'.$slug);
-			
+		$submitCredentials = $submitCredentials && !empty($this->credvars);
 
 		if ( $submitCredentials ) {
 			$credentials = array();
@@ -219,7 +221,7 @@ class OpenToolsPluginUpdateChecker extends PluginUpdateChecker_2_1 {
 		$updateinfo = $this->requestInfo(array());
 		if ($updateinfo && isset($updateinfo->download_url)) {
 			$downloadurl = $updateinfo->download_url;
-			$downloadurl .= (parse_url($downloadurl, PHP_URL_QUERY) ? '&' : '?') . 'check_access=1';
+			$downloadurl = apply_filters('puc_check_download_query_args-'.$this->slug, $downloadurl);
 		
 			$headers = get_headers($downloadurl);
 			list($version, $status_code, $msg) = explode(' ',$headers[0], 3);
@@ -232,6 +234,10 @@ class OpenToolsPluginUpdateChecker extends PluginUpdateChecker_2_1 {
 		}
 		return $success;
 	}
+	
+	public function addAccessCheckQueryArgFilter($callback){
+		add_filter('puc_check_download_query_args-'.$this->slug, $callback);
+	}
 
 };
 
diff --git a/releases/opentools-woocommerce-ordernumbers-advanced_v1.2.1.zip b/releases/opentools-woocommerce-ordernumbers-advanced_v1.2.1.zip
index 33e53b337474afa5269ba455c27bdec287b46014..964474778eea386f29561ade58c02ba8d86d9101 100644
Binary files a/releases/opentools-woocommerce-ordernumbers-advanced_v1.2.1.zip and b/releases/opentools-woocommerce-ordernumbers-advanced_v1.2.1.zip differ
diff --git a/woocommerce-advanced-ordernumbers.php b/woocommerce-advanced-ordernumbers.php
index d473fa33c314efa9e4c073c18e4ba61bff26c5bd..d46fda0e3dc438995d7661bdb5ee48b5ee916e1d 100644
--- a/woocommerce-advanced-ordernumbers.php
+++ b/woocommerce-advanced-ordernumbers.php
@@ -35,6 +35,11 @@ $myUpdateChecker->declareCredentials(array(
 	'order_number' => __('Order Number:'), 
 	'order_pass'   => __('Order Password:'),
 ));
+$myUpdateChecker->addAccessCheckQueryArgFilter('oton_addAccessCheckArg');
+function oton_addAccessCheckArg($downloadurl) {
+	return $downloadurl . (parse_url($downloadurl, PHP_URL_QUERY) ? '&' : '?') . 'check_access=1';
+}
+
 // $myUpdateChecker->checkForUpdates();
 // *****************************************************************