diff --git a/src/Utils/WhichEnv/WhichEnv.php b/src/Utils/WhichEnv/WhichEnv.php
index ca9f712..31060db 100644
--- a/src/Utils/WhichEnv/WhichEnv.php
+++ b/src/Utils/WhichEnv/WhichEnv.php
@@ -6,7 +6,8 @@ namespace Bsr\Utils\WhichEnv;
  * based on a cutom rule
  */
 class WhichEnv {
-    private $rule;
+
+    static private $rule;
 
     static public function registerRule(WhichEnvRuleInterface $rule)
     {