diff --git a/setup.py b/setup.py
index 28c42ba..8be5b94 100644
--- a/setup.py
+++ b/setup.py
@@ -62,7 +62,7 @@ def run(self):
 
 
 setup(name='up_enhsp',
-      version='0.0.24',
+      version='0.0.25',
       description='up_enhsp',
       author='UNIBS Team',
       author_email='enrico.scala@unibs.it',
diff --git a/up_enhsp/enhsp_planner.py b/up_enhsp/enhsp_planner.py
index a23eca3..8cd535b 100644
--- a/up_enhsp/enhsp_planner.py
+++ b/up_enhsp/enhsp_planner.py
@@ -92,7 +92,7 @@ def get_credits(**kwargs) -> Optional['Credits']:
 
 
 class ENHSPAnytimeEngine(ENHSPEngine, PDDLAnytimePlanner):
-    def __init__(self, params: str | None = None):
+    def __init__(self, params: Optional[str] = None):
         ENHSPEngine.__init__(self,params)
         PDDLAnytimePlanner.__init__(self)