diff --git a/htdocs/categories/edit.php b/htdocs/categories/edit.php
index 954241e655d..2a42576a9d7 100644
--- a/htdocs/categories/edit.php
+++ b/htdocs/categories/edit.php
@@ -50,7 +50,7 @@ if ($_POST["action"] == 'update' && $user->rights->categorie->creer)
 	
 	$categorie->label          = $_POST["nom"];
 	$categorie->description    = $_POST["description"];
-	$categorie->socid          = $_POST["socid"];
+	$categorie->socid          = ($_POST["socid"] ? $_POST["socid"] : 'null');
 	$categorie->visible        = $_POST["visible"];
 	
 	if($_POST['catMere'] != "-1")
diff --git a/htdocs/categories/fiche.php b/htdocs/categories/fiche.php
index 983c35e3819..6ea75c4c76b 100644
--- a/htdocs/categories/fiche.php
+++ b/htdocs/categories/fiche.php
@@ -100,7 +100,7 @@ if ($_POST["action"] == 'add' && $user->rights->categorie->creer)
 
 	$categorie->label          = $_POST["nom"];
 	$categorie->description    = $_POST["description"];
-	$categorie->socid          = $_POST["socid"];
+	$categorie->socid          = ($_POST["socid"] ? $_POST["socid"] : 'null');
 	$categorie->visible        = $_POST["visible"];
 	$categorie->type		       = $_POST["type"];