diff --git a/materiels.tar.gz b/materiels.tar.gz
index 1886c2b..9b42823 100644
Binary files a/materiels.tar.gz and b/materiels.tar.gz differ
diff --git a/src/lib/Equipment.php b/src/lib/Equipment.php
index 1350e69..b3b671d 100644
--- a/src/lib/Equipment.php
+++ b/src/lib/Equipment.php
@@ -132,8 +132,23 @@ class Equipment
           array_push($eqmts_available, $eqmt);
         }
       }
-      $eqmts_available_by_cat[$cat] = $eqmts_available;
+      if ($eqmts_available) {
+        $eqmts_available_by_cat[$cat] = $eqmts_available;
+      }
     }
     return $eqmts_available_by_cat;
   }
+
+  public function CalculateAvailableByDate($id, $date)
+  {
+    $entries = DB::getInstance()->firstColumn(
+      "SELECT sum(equipment_number) FROM plugin_materiels_entry WHERE kind IN (
+        'Achat', 'Don', 'Récupération',
+        'Retour de location / prêt') AND equipment_id = '{$id}' AND entry_date <= '{$date}';");
+    $outputs = DB::getInstance()->firstColumn(
+      "SELECT sum(equipment_number) FROM plugin_materiels_output WHERE kind IN (
+        'Vente', 'Don', 'Besoin', 'Autre (perte, vol, ...)',
+        'Location / Prêt') AND equipment_id = '{$id}' AND output_date <= '{$date}';");
+    return $entries - $outputs;
+  }
 }
diff --git a/src/lib/Output.php b/src/lib/Output.php
index de94cec..b8234e4 100644
--- a/src/lib/Output.php
+++ b/src/lib/Output.php
@@ -3,6 +3,7 @@
 namespace Garradin\Plugin\Materiels;
 
 use Garradin\DB;
+use Garradin\Plugin\Materiels\Equipment;
 
 class Output
 {
@@ -32,4 +33,26 @@ class Output
 	{
 		return DB::getInstance()->get('SELECT * FROM plugin_materiels_output ORDER BY output_date DESC;');
 	}
+
+  public function PossibilityOwnedEqmtOutput($id, $eqmt_number, $date)
+	{
+    $after_output_dates = DB::getInstance()->get(
+      "SELECT output_date FROM plugin_materiels_output WHERE kind IN (
+        'Vente', 'Don', 'Besoin', 'Autre (perte, vol, ...)',
+        'Location / Prêt') AND equipment_id = '{$id}' AND output_date > '{$date}';");
+    $output_dates = array($date);
+    foreach ($after_output_dates as $row)
+    {
+      array_push($output_dates, $row->output_date);
+    }
+    $eqmt = new Equipment;
+    foreach ($output_dates as $output_date) {
+      $available_eqmt = $eqmt->CalculateAvailableByDate($id, $output_date);
+      if ($available_eqmt - $eqmt_number < 0)
+      {
+        return false;
+      }
+    }
+    return true;
+	}
 }
diff --git a/src/templates/sorties/index.tpl b/src/templates/sorties/index.tpl
index b4f83fb..cecde2c 100644
--- a/src/templates/sorties/index.tpl
+++ b/src/templates/sorties/index.tpl
@@ -20,7 +20,7 @@
     <tbody>
       {foreach from=$outputs item="output"}
         <tr>
-          <td>{$entry.output_date|date_format:'%d/%m/%y'}</td>
+          <td>{$output.output_date|date_format:'%d/%m/%y'}</td>
           <td>{$output.kind}</td>
           <td>{$output.equipment_number}</td>
           <td>{$output.equipment}</td>
diff --git a/src/templates/sorties/stock_disponible.tpl b/src/templates/sorties/stock_disponible.tpl
index 1d6e4cc..c13c432 100644
--- a/src/templates/sorties/stock_disponible.tpl
+++ b/src/templates/sorties/stock_disponible.tpl
@@ -5,13 +5,11 @@
     <dd>
       <select name="equipment_id" id="f_eqmt">
         {foreach from=$eqmts_by_cat key='cat' item="eqmts"}
-          {if $eqmts}
-            <optgroup label="-- {$cat} --">
-              {foreach from=$eqmts item="eqmt"}
-                <option value="{$eqmt.id}">{$eqmt.designation} - (dispo: {$eqmt.available})</option>
-              {/foreach}
-            </optgroup>
-          {/if}
+          <optgroup label="-- {$cat} --">
+            {foreach from=$eqmts item="eqmt"}
+              <option value="{$eqmt.id}"{if ($selected_eqmt !== "") && ($selected_eqmt == $eqmt.id)} selected="selected"{/if}>{$eqmt.designation} - (dispo: {$eqmt.available})</option>
+            {/foreach}
+          </optgroup>
         {/foreach}
       </select>
     </dd>
diff --git a/src/www/admin/sorties/stock_disponible.php b/src/www/admin/sorties/stock_disponible.php
index 3013298..4e45c48 100644
--- a/src/www/admin/sorties/stock_disponible.php
+++ b/src/www/admin/sorties/stock_disponible.php
@@ -10,23 +10,9 @@ require_once __DIR__ . '/../_inc.php';
 
 $output = new Output;
 $eqmt = new Equipment;
+
 $eqmts_by_cat = $eqmt->GetAvailableListByCategory();
-
-$csrf_key = 'add_output';
-
-if (f('save') && $form->check($csrf_key) && !$form->hasErrors())
-{
-  $output_date_format = date_create_from_format(
-    "d/m/Y", f('entry_date'))->format("Y-m-d");
-  $output->add([
-    'kind' => f('kind'),
-    'equipment_number' => (int) f('equipment_number'),
-    'equipment_id' => f('equipment_id'),
-    'output_date' => $output_date_format,
-    'additional_comment' => f('additional_comment'),
-  ]);
-  Utils::redirect(PLUGIN_URL . 'entrees/index.php');
-}
+$selected_eqmt = "";
 
 $kinds = $output->listKinds();
 $selected_kind = $kinds[0];
@@ -37,13 +23,45 @@ $default_date = $date;
 
 $default_comment = "";
 
+$csrf_key = 'add_output';
+
+if (f('save') && $form->check($csrf_key) && !$form->hasErrors())
+{
+  $eqmt_id = f('equipment_id');
+  $eqmt_number = (int) f('equipment_number');
+  $output_date_format = date_create_from_format(
+    "d/m/Y", f('output_date'))->format("Y-m-d");
+  if ($output->PossibilityOwnedEqmtOutput($eqmt_id, $eqmt_number, $output_date_format))
+  {
+    $output->add([
+      'kind' => f('kind'),
+      'equipment_number' => $eqmt_number,
+      'equipment_id' => $eqmt_id,
+      'output_date' => $output_date_format,
+      'additional_comment' => f('additional_comment'),
+    ]);
+    Utils::redirect(PLUGIN_URL . 'sorties/index.php');
+  } else
+  {
+    $output_date = f('output_date');
+    $selected_eqmt = $eqmt_id;
+    $selected_kind = f('kind');
+    $default_date = $output_date;
+    $default_comment = f('additional_comment');
+
+    $equiment = $eqmt->get(f('equipment_id'));
+    $form->addError(
+      "Il est impossible de sortir " . (string) $eqmt_number . " " . $equiment->designation . " à la date du " . (string) $output_date . '.');
+  }
+}
+
 $cancel_link = PLUGIN_URL . 'sorties/index.php';
 $legend_part = "en stock disponible";
 $tpl_materiel_name = "stock_disponible";
 
 $tpl->assign(compact(
   'csrf_key', 'cancel_link', 'legend_part', 'tpl_materiel_name',
-  'kinds', 'selected_kind', 'default_date', 'default_comment',
+  'kinds', 'selected_eqmt', 'selected_kind', 'default_date', 'default_comment',
   'eqmts_by_cat'));
 
 $tpl->display(PLUGIN_ROOT . '/templates/sorties/ajouter_sortie.tpl');