diff --git a/rl_coach/memories/non_episodic/experience_replay.py b/rl_coach/memories/non_episodic/experience_replay.py
index 798854c..4887e49 100644
--- a/rl_coach/memories/non_episodic/experience_replay.py
+++ b/rl_coach/memories/non_episodic/experience_replay.py
@@ -51,7 +51,6 @@ class ExperienceReplay(Memory):
         if max_size[0] != MemoryGranularity.Transitions:
             raise ValueError("Experience replay size can only be configured in terms of transitions")
         self.transitions = []
-        self._num_transitions = 0
         self.allow_duplicates_in_batch_sampling = allow_duplicates_in_batch_sampling
 
         self.reader_writer_lock = ReaderWriterLock()
@@ -66,7 +65,7 @@ class ExperienceReplay(Memory):
         """
         Get the number of transitions in the ER
         """
-        return self._num_transitions
+        return len(self.transitions)
 
     def sample(self, size: int) -> List[Transition]:
         """
@@ -119,7 +118,6 @@ class ExperienceReplay(Memory):
         if lock:
             self.reader_writer_lock.lock_writing_and_reading()
 
-        self._num_transitions += 1
         self.transitions.append(transition)
         self._enforce_max_length()
 
@@ -149,6 +147,7 @@ class ExperienceReplay(Memory):
     def remove_transition(self, transition_index: int, lock: bool=True) -> None:
         """
         Remove the transition in the given index.
+
         This does not remove the transition from the segment trees! it is just used to remove the transition
         from the transitions list
         :param transition_index: the index of the transition to remove
@@ -158,7 +157,6 @@ class ExperienceReplay(Memory):
             self.reader_writer_lock.lock_writing_and_reading()
 
         if self.num_transitions() > transition_index:
-            self._num_transitions -= 1
             del self.transitions[transition_index]
 
         if lock:
@@ -191,7 +189,6 @@ class ExperienceReplay(Memory):
             self.reader_writer_lock.lock_writing_and_reading()
 
         self.transitions = []
-        self._num_transitions = 0
 
         if lock:
             self.reader_writer_lock.release_writing_and_reading()