diff --git a/adminstuds.php b/adminstuds.php
index 29f3d27..b47ea03 100644
--- a/adminstuds.php
+++ b/adminstuds.php
@@ -246,6 +246,7 @@ if (!empty($_POST['save'])) { // Save edition of an old vote
 
 if (!empty($_GET['delete_vote'])) {
     $vote_id = filter_input(INPUT_GET, 'delete_vote', FILTER_VALIDATE_INT);
+    $vote_id = Utils::base64url_decode($vote_id);
     if ($adminPollService->deleteVote($poll_id, $vote_id)) {
         $message = new Message('success', __('adminstuds', 'Vote deleted'));
     } else {
@@ -361,6 +362,7 @@ if (isset($_POST['confirm_delete_poll'])) {
 
 if (!empty($_GET['delete_column'])) {
     $column = filter_input(INPUT_GET, 'delete_column', FILTER_DEFAULT);
+    $column = Utils::base64url_decode($column);
 
     if ($poll->format === 'D') {
         $ex = explode('@', $column);
diff --git a/app/classes/Framadate/Utils.php b/app/classes/Framadate/Utils.php
index 3565a70..b340bad 100644
--- a/app/classes/Framadate/Utils.php
+++ b/app/classes/Framadate/Utils.php
@@ -105,7 +105,7 @@ class Utils {
      */
     public static function getUrlSondage($id, $admin = false, $vote_id = '', $action = null, $action_value = null) {
         // URL-Encode $action_value
-        $action_value = $action_value == null ? null : urlencode($action_value);
+        $action_value = $action_value == null ? null : Utils::base64url_encode($action_value);
 
         if (URL_PROPRE) {
             if ($admin === true) {
@@ -115,8 +115,12 @@ class Utils {
             }
             if ($vote_id != '') {
                 $url .= '/vote/' . $vote_id . "#edit";
-            } elseif ($action != null && $action_value != null) {
-                $url .= '/action/' . $action . '/' . $action_value;
+            } elseif ($action != null) {
+                if ($action_value != null) {
+                    $url .= '/action/' . $action . '/' . $action_value;
+                } else {
+                    $url .= '/action/' . $action;
+                }
             }
         } else {
             if ($admin === true) {
@@ -126,8 +130,12 @@ class Utils {
             }
             if ($vote_id != '') {
                 $url .= '&vote=' . $vote_id . "#edit";
-            } elseif ($action != null && $action_value != null)  {
-                $url .= '&' . $action . "=" . $action_value;
+            } elseif ($action != null)  {
+                if ($action_value != null) {
+                    $url .= '&' . $action . "=" . $action_value;
+                } else {
+                    $url .= '&' . $action . "=";
+                }
             }
         }
 
@@ -200,4 +208,12 @@ class Utils {
     public static function fromPostOrDefault($postKey, $default = '') {
         return !empty($_POST[$postKey]) ? Utils::htmlEscape($_POST[$postKey]) : $default;
     }
+
+    public static function base64url_encode($input) {
+        return rtrim(strtr(base64_encode($input), '+/', '-_'), '=');
+    }
+
+    public static function base64url_decode($input) {
+        return base64_decode(str_pad(strtr($input, '-_', '+/'), strlen($input) % 4, '=', STR_PAD_RIGHT));
+    }
 }
diff --git a/htaccess.txt b/htaccess.txt
index a59fcd7..640cb13 100644
--- a/htaccess.txt
+++ b/htaccess.txt
@@ -9,9 +9,9 @@
   RewriteRule . - [L]
 
   RewriteRule ^([a-zA-Z0-9]{16})$ studs.php?poll=$1 [L]
-  RewriteRule ^([a-zA-Z0-9]{16})/action/([a-zA-Z_-]+)/(.+)$ studs.php?poll=$1&$2=$3 [B]
+  RewriteRule ^([a-zA-Z0-9]{16})/action/([a-zA-Z_-]+)/(.+)$ studs.php?poll=$1&$2=$3
   RewriteRule ^([a-zA-Z0-9]{16})/vote/([a-zA-Z0-9]{16})$ studs.php?poll=$1&vote=$2
   RewriteRule ^([a-zA-Z0-9]{24})/admin$ adminstuds.php?poll=$1
   RewriteRule ^([a-zA-Z0-9]{24})/admin/vote/([a-zA-Z0-9]{16})$ adminstuds.php?poll=$1&vote=$2
-  RewriteRule ^([a-zA-Z0-9]{24})/admin/action/([a-zA-Z_-]+)/(.+)$ adminstuds.php?poll=$1&$2=$3 [B]
+  RewriteRule ^([a-zA-Z0-9]{24})/admin/action/([a-zA-Z_-]+)(/(.+))?$ adminstuds.php?poll=$1&$2=$4
 </IfModule>
\ No newline at end of file
diff --git a/tpl/part/vote_table_classic.tpl b/tpl/part/vote_table_classic.tpl
index a00af34..fa496ef 100644
--- a/tpl/part/vote_table_classic.tpl
+++ b/tpl/part/vote_table_classic.tpl
@@ -21,7 +21,7 @@
                             </td>
                     {/foreach}
                     <td>
-                        <a href="{poll_url id=$admin_poll_id admin=true action='add_slot' action_value=true}"
+                        <a href="{poll_url id=$admin_poll_id admin=true action='add_slot'}"
                            class="btn btn-link btn-sm" title="{__('adminstuds', 'Add a column')}">
                             <i class="glyphicon glyphicon-plus text-success"></i><span class="sr-only">{__('Poll results', 'Add a column')}</span>
                         </a>
diff --git a/tpl/part/vote_table_date.tpl b/tpl/part/vote_table_date.tpl
index 4ba4347..2afb20b 100644
--- a/tpl/part/vote_table_date.tpl
+++ b/tpl/part/vote_table_date.tpl
@@ -27,7 +27,7 @@
                         {/foreach}
                     {/foreach}
                     <td>
-                        <a href="{poll_url id=$admin_poll_id admin=true action='add_slot' action_value=true}"
+                        <a href="{poll_url id=$admin_poll_id admin=true action='add_slot'}"
                            class="btn btn-link btn-sm" title="{__('adminstuds', 'Add a column')}">
                             <i class="glyphicon glyphicon-plus text-success"></i><span class="sr-only">{__('Poll results', 'Add a column')}</span>
                         </a>