diff --git a/library/ZendAfi/View/Helper/SitoTree.php b/library/ZendAfi/View/Helper/SitoTree.php
index 2dc3dcc74b6ce4eccc4db67536ddf7167c9d3a88..953646e088fa8b3bc7d6897ba31d884c7f69a61b 100644
--- a/library/ZendAfi/View/Helper/SitoTree.php
+++ b/library/ZendAfi/View/Helper/SitoTree.php
@@ -30,6 +30,9 @@ class ZendAfi_View_Helper_SitoTree extends ZendAfi_View_Helper_BaseHelper {
 
 
 	protected function renderHierarchicalCategories($category, $max_display) {
+		if (!$category)
+			return $this->_('Aucune catégorie sélectionnée.');
+
 		$html = '';
 		$children = $category->getChildren();
 		foreach (array_slice($children, 0, $max_display) as $child_category)