diff --git a/src/festim/stepsize.py b/src/festim/stepsize.py
index 8819f9dbd..1e9ff35e0 100644
--- a/src/festim/stepsize.py
+++ b/src/festim/stepsize.py
@@ -120,7 +120,7 @@ def get_max_stepsize(self, t):
             return self._max_stepsize(t)
         return self._max_stepsize
 
-    def modify_value(self, value, nb_iterations, t):
+    def modify_value(self, value, nb_iterations, t=None):
         if not self.is_adapt(t):
             return value