diff --git a/lib/Alchemy/Phrasea/Core/Version.php b/lib/Alchemy/Phrasea/Core/Version.php
index c209691c0b..5f488cdd5a 100644
--- a/lib/Alchemy/Phrasea/Core/Version.php
+++ b/lib/Alchemy/Phrasea/Core/Version.php
@@ -16,7 +16,7 @@ class Version
     /**
      * @var string
      */
-    private $number = '4.1.0-alpha.19a';
+    private $number = '4.1.0-alpha.20a';
 
     /**
      * @var string
diff --git a/lib/classes/patch/410alpha20a.php b/lib/classes/patch/410alpha20a.php
new file mode 100644
index 0000000000..ff02a35c96
--- /dev/null
+++ b/lib/classes/patch/410alpha20a.php
@@ -0,0 +1,111 @@
+<?php
+
+/*
+ * This file is part of Phraseanet
+ *
+ * (c) 2005-2019 Alchemy
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+use Alchemy\Phrasea\Application;
+
+class patch_410alpha20a implements patchInterface
+{
+    /** @var string */
+    private $release = '4.1.0-alpha.20a';
+
+    /** @var array */
+    private $concern = [base::DATA_BOX];
+
+    /**
+     * Returns the release version.
+     *
+     * @return string
+     */
+    public function get_release()
+    {
+        return $this->release;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function concern()
+    {
+        return $this->concern;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function require_all_upgrades()
+    {
+        return false;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getDoctrineMigrations()
+    {
+        return [];
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function apply(base $databox, Application $app)
+    {
+        // fix the Longitude value
+
+        $sql = 'SELECT id, record_id, name, value FROM technical_datas WHERE trim(name) = "LongitudeRef" ';
+        $stmt = $databox->get_connection()->prepare($sql);
+        $stmt->execute();
+        $rs = $stmt->fetchAll(PDO::FETCH_ASSOC);
+        $stmt->closeCursor();
+
+        foreach ($rs as $row) {
+            if (trim($row['value']) === 'W' ) {
+                $sql = 'UPDATE technical_datas SET value = CONCAT("-", value) WHERE trim(name) = "Longitude" AND record_id =:record_id';
+                $stmt = $databox->get_connection()->prepare($sql);
+                $stmt->execute([':record_id' => $row['record_id']]);
+            }
+
+            $sqlDelete = 'DELETE FROM technical_datas WHERE id =:id';
+
+            $stmt1 = $databox->get_connection()->prepare($sqlDelete);
+            $stmt1->execute([':id' => $row['id']]);
+            $stmt1->closeCursor();
+        }
+
+        $stmt->closeCursor();
+
+        // fix the Latitude value
+
+        $sql = 'SELECT id, record_id, name, value FROM technical_datas WHERE trim(name) = "LatitudeRef" ';
+        $stmt = $databox->get_connection()->prepare($sql);
+        $stmt->execute();
+        $rs = $stmt->fetchAll(PDO::FETCH_ASSOC);
+        $stmt->closeCursor();
+
+        foreach ($rs as $row) {
+            if (trim($row['value']) === 'S' ) {
+                $sql = 'UPDATE technical_datas SET value = CONCAT("-", value) WHERE trim(name) = "Latitude" AND record_id =:record_id';
+                $stmt = $databox->get_connection()->prepare($sql);
+                $stmt->execute([':record_id' => $row['record_id']]);
+            }
+
+            $sqlDelete = 'DELETE FROM technical_datas WHERE id =:id';
+
+            $stmt1 = $databox->get_connection()->prepare($sqlDelete);
+            $stmt1->execute([':id' => $row['id']]);
+            $stmt1->closeCursor();
+        }
+
+        $stmt->closeCursor();
+
+        return true;
+    }
+}