diff --git a/src/acom_music_box/evolving_conditions.py b/src/acom_music_box/evolving_conditions.py
index 9d689ded..e763fd1b 100644
--- a/src/acom_music_box/evolving_conditions.py
+++ b/src/acom_music_box/evolving_conditions.py
@@ -145,7 +145,7 @@ def add_condition(self, time_point, conditions):
         self.conditions.append(conditions)
 
     @classmethod
-    def read_conditions_from_file(self, file_path):
+    def read_conditions_from_file(cls, file_path):
         """
         Read conditions from a file and update the evolving conditions.
 
@@ -191,7 +191,7 @@ def read_conditions_from_file(self, file_path):
                     reaction_rates))
 
 
-        return self(times=times, conditions=conditions)
+        return cls(times=times, conditions=conditions)
 
     # allows len overload for this class