diff --git a/lib/Alchemy/Phrasea/Setup/Installer.php b/lib/Alchemy/Phrasea/Setup/Installer.php
index a26cc9d3cc..4c9c76d0f8 100644
--- a/lib/Alchemy/Phrasea/Setup/Installer.php
+++ b/lib/Alchemy/Phrasea/Setup/Installer.php
@@ -192,6 +192,9 @@ private function createConfigFile(Connection $abConn, $serverName, $binaryData,
         $config['servername'] = $serverName;
         $config['main']['key'] = $this->app['random.medium']->generateString(16);
 
+        // generate from the random instance key
+        $config['phraseanet-service']['phraseanet_local_id'] = md5($config['main']['key']);
+
         // define storage config
         $defaultStoragePaths = [
             'subdefs'           => __DIR__ . '/../../../../datas',
diff --git a/lib/classes/patch/418RC7PHRAS3935.php b/lib/classes/patch/418RC7PHRAS3935.php
new file mode 100644
index 0000000000..d033e7deed
--- /dev/null
+++ b/lib/classes/patch/418RC7PHRAS3935.php
@@ -0,0 +1,79 @@
+<?php
+
+
+use Alchemy\Phrasea\Application;
+use Alchemy\Phrasea\Core\Configuration\PropertyAccess;
+
+class patch_418RC7PHRAS3935 implements patchInterface
+{
+    /** @var string */
+    private $release = '4.1.8-rc7';
+
+    /** @var array */
+    private $concern = [base::APPLICATION_BOX];
+
+    /**
+     * {@inheritdoc}
+     */
+    public function get_release()
+    {
+        return $this->release;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getDoctrineMigrations()
+    {
+        return [];
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function require_all_upgrades()
+    {
+        return false;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function concern()
+    {
+        return $this->concern;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function apply(base $base, Application $app)
+    {
+        if ($base->get_base_type() === base::DATA_BOX) {
+            $this->patch_databox($base, $app);
+        } elseif ($base->get_base_type() === base::APPLICATION_BOX) {
+            $this->patch_appbox($base, $app);
+        }
+
+        return true;
+    }
+
+    private function patch_databox(databox $databox, Application $app)
+    {
+    }
+
+    private function patch_appbox(base $appbox, Application $app)
+    {
+        /** @var PropertyAccess $conf */
+        $conf = $app['conf'];
+
+        if (!$conf->has(['phraseanet-service', 'phraseanet_local_id'])) {
+            // instance key is already a random value
+            $instanceKey = $conf->get(['main', 'key']);
+
+            $phraseanetLocalId = md5($instanceKey);
+
+            $conf->set(['phraseanet-service', 'phraseanet_local_id'], $phraseanetLocalId);
+        }
+    }
+}