diff --git a/src/simudator/core/module.py b/src/simudator/core/module.py
index 82beff32cff66772847216379af3f57ac89491ae..107abfbb0d96e264c5de745c13f8c5f934bcfff4 100644
--- a/src/simudator/core/module.py
+++ b/src/simudator/core/module.py
@@ -123,7 +123,7 @@ class Module:
         ----------
         file_path : str
             Path to file to save to.
-        content : str    
+        content : str
             Content to save to file.
 
         Returns
@@ -133,7 +133,6 @@ class Module:
         try:
             with open(file_path, "a") as file:
                 file.write(content)
-                file.close()
         except OSError:
             return False
         return True
diff --git a/src/simudator/core/modules/demux.py b/src/simudator/core/modules/demux.py
index d7f47a20dd88a4162bbb29ce7e6210cab9ff0d27..fa77b582b8a4925d8c359cbef61ec3a9d7a5f614 100644
--- a/src/simudator/core/modules/demux.py
+++ b/src/simudator/core/modules/demux.py
@@ -56,6 +56,8 @@ class Demux(Module):
 
     def update_logic(self):
         """
+        Do nothing.
+
         The demux has no logic
         """
         pass
@@ -72,10 +74,8 @@ class Demux(Module):
         return state
 
     def save_state_to_file(self, file_path: str) -> bool:
-        """
-        The demux has no state to save.
-        """
-        return True
+        content = self.name + ":\nvalue: " + str(self.value) + "\n\n"
+        return super()._helper_save_state_to_file(file_path, content)
 
     def set_state(self, state: dict) -> None:
         """
diff --git a/src/simudator/core/modules/mux.py b/src/simudator/core/modules/mux.py
index db5a5b40bd777bc11164437729c3943296a27ddb..70a9ff77b4d71488851957ef66fe0dff0f88e594 100644
--- a/src/simudator/core/modules/mux.py
+++ b/src/simudator/core/modules/mux.py
@@ -57,6 +57,8 @@ class Mux(Module):
 
     def update_logic(self):
         """
+        Do nothing.
+
         The mux has no logic.
         """
         pass