diff --git a/src/cpl_reactive_extensions/behavior_subject.py b/src/cpl_reactive_extensions/behavior_subject.py
index 18b087c0..67121644 100644
--- a/src/cpl_reactive_extensions/behavior_subject.py
+++ b/src/cpl_reactive_extensions/behavior_subject.py
@@ -1,10 +1,10 @@
 from cpl_core.type import T
-from cpl_reactive_extensions.observable import Observable
+from cpl_reactive_extensions.subject import Subject
 
 
-class BehaviorSubject(Observable):
+class BehaviorSubject(Subject):
     def __init__(self, _t: type, value: T):
-        Observable.__init__(self, lambda x: x)
+        Subject.__init__(self, _t)
 
         if not isinstance(value, _t):
             raise TypeError(f"Expected {_t.__name__} not {type(value).__name__}")
@@ -17,7 +17,6 @@ class BehaviorSubject(Observable):
         return self._value
 
     def next(self, value: T):
-        if not isinstance(value, self._t):
-            raise TypeError(f"Expected {self._t.__name__} not {type(value).__name__}")
+        super().next(value)
 
         self._value = value
diff --git a/src/cpl_reactive_extensions/subject.py b/src/cpl_reactive_extensions/subject.py
index 0ae3f134..2b2c40fc 100644
--- a/src/cpl_reactive_extensions/subject.py
+++ b/src/cpl_reactive_extensions/subject.py
@@ -34,7 +34,7 @@ class Subject(Observable, Observer):
         self._raise_if_closed()
 
         if not isinstance(value, self._t):
-            raise TypeError()
+            raise TypeError(f"Expected {self._t.__name__} not {type(value).__name__}")
 
         if self.is_stopped:
             return