diff --git a/tiramisu/function.py b/tiramisu/function.py
index 7a3348e..ea51dc6 100644
--- a/tiramisu/function.py
+++ b/tiramisu/function.py
@@ -25,7 +25,7 @@ class Params:
         if isinstance(args, Param):
             args = (args,)
         else:
-            if not isinstance(args, (tuple, list)):
+            if not isinstance(args, tuple):
                 raise ValueError(_('args in params must be a list'))
             for arg in args:
                 if not isinstance(arg, Param):
@@ -35,8 +35,6 @@ class Params:
         for arg in kwargs.values():
             if not isinstance(arg, Param):
                 raise ValueError(_('arg in params must be a Param'))
-        if isinstance(args, list):
-            args = tuple(args)
         self.args = args
         self.kwargs = kwargs