diff --git a/sudoku.php b/sudoku.php
index e80015c..94b4ab1 100755
--- a/sudoku.php
+++ b/sudoku.php
@@ -73,7 +73,7 @@
                     <ul class="nav nav-pills flex-column">
                         <li><a href="." class="nav-link link-body-emphasis">Nouvelle grille</a></li>
                         <li><a href="" class="nav-link link-body-emphasis">Lien vers cette grille</a></li>
-                        <li><a href="?................................................................................." class="nav-link link-body-emphasis">Grille vierge</a></li>
+                        <li><a href="?---------------------------------------------------------------------------------" class="nav-link link-body-emphasis">Grille vierge</a></li>
                         <li><a id="fixGridLink" href="" class="nav-link link-body-emphasis">Figer la grille</a></li>
                         <li><a href="https://git.malingrey.fr/adrien/Sudoku" class="nav-link link-body-emphasis">Code source</a></li>
                         <li><a href=".." class="nav-link link-body-emphasis">Autres jeux</a></li>
diff --git a/thumbnail.php b/thumbnail.php
index 1740ee4..1a04c0d 100755
--- a/thumbnail.php
+++ b/thumbnail.php
@@ -1,9 +1,9 @@
 <?php
     require("classes.php");
-    if (isset($_GET["grid"]) && preg_match("/^[1-9.]{81}$/", $_GET["grid"]))
+    if (isset($_GET["grid"]) && preg_match("/^[1-9-]{81}$/", $_GET["grid"]))
         $currentGrid = $_GET["grid"];
     else
-        $currentGrid = ".528.3....4.9.1...39.562......73.129...1.64.7...42.3656.13.5...28.6.4...4.5287...";
+        $currentGrid = "-528-3----4-9-1---39-562------73-129---1-64-7---42-3656-13-5---28-6-4---4-5287---";
     header ("Content-type: image/png");
     if (isset($_GET['size']))
         $size = (int) $_GET['size'];