diff --git a/dopamine/replay_memory/circular_replay_buffer.py b/dopamine/replay_memory/circular_replay_buffer.py
index 7170434b..a992b887 100644
--- a/dopamine/replay_memory/circular_replay_buffer.py
+++ b/dopamine/replay_memory/circular_replay_buffer.py
@@ -265,17 +265,40 @@ def _add(self, *args):
     Args:
       *args: All the elements in a transition.
     """
-    cursor = self.cursor()
+    self._check_args_length(*args)
+    transition = {e.name: args[idx]
+                  for idx, e in enumerate(self.get_add_args_signature())}
+    self._add_transition(transition)
+
+  def _add_transition(self, transition):
+    """Internal add method to add transition dictionary to storage arrays.
 
-    arg_names = [e.name for e in self.get_add_args_signature()]
-    for arg_name, arg in zip(arg_names, args):
-      self._store[arg_name][cursor] = arg
+    Args:
+      transition: The dictionary of names and values of the transition
+                  to add to the storage.
+    """
+    cursor = self.cursor()
+    for arg_name in transition:
+      self._store[arg_name][cursor] = transition[arg_name]
 
     self.add_count += 1
     self.invalid_range = invalid_range(
         self.cursor(), self._replay_capacity, self._stack_size,
         self._update_horizon)
 
+  def _check_args_length(self, *args):
+    """Check if args passed to the add method have the same length as storage.
+
+    Args:
+      *args: Args for elements used in storage.
+
+    Raises:
+      ValueError: If args have wrong length.
+    """
+    if len(args) != len(self.get_add_args_signature()):
+      raise ValueError('Add expects {} elements, received {}'.format(
+          len(self.get_add_args_signature()), len(args)))
+
   def _check_add_types(self, *args):
     """Checks if args passed to the add method match those of the storage.
 
@@ -285,9 +308,7 @@ def _check_add_types(self, *args):
     Raises:
       ValueError: If args have wrong shape or dtype.
     """
-    if len(args) != len(self.get_add_args_signature()):
-      raise ValueError('Add expects {} elements, received {}'.format(
-          len(self.get_add_args_signature()), len(args)))
+    self._check_args_length(*args)
     for arg_element, store_element in zip(args, self.get_add_args_signature()):
       if isinstance(arg_element, np.ndarray):
         arg_shape = arg_element.shape
diff --git a/dopamine/replay_memory/prioritized_replay_buffer.py b/dopamine/replay_memory/prioritized_replay_buffer.py
index 9ed778ba..bfd094c1 100644
--- a/dopamine/replay_memory/prioritized_replay_buffer.py
+++ b/dopamine/replay_memory/prioritized_replay_buffer.py
@@ -124,20 +124,20 @@ def _add(self, *args):
     Args:
       *args: All the elements in a transition.
     """
+    self._check_args_length(*args)
+
     # Use Schaul et al.'s (2015) scheme of setting the priority of new elements
     # to the maximum priority so far.
-    parent_add_args = []
-    # Picks out 'priority' from arguments and passes the other arguments to the
-    # parent method.
+    # Picks out 'priority' from arguments and adds it to the sum_tree.
+    transition = {}
     for i, element in enumerate(self.get_add_args_signature()):
       if element.name == 'priority':
         priority = args[i]
       else:
-        parent_add_args.append(args[i])
+        transition[element.name] = args[i]
 
     self.sum_tree.set(self.cursor(), priority)
-
-    super(OutOfGraphPrioritizedReplayBuffer, self)._add(*parent_add_args)
+    super(OutOfGraphPrioritizedReplayBuffer, self)._add_transition(transition)
 
   def sample_index_batch(self, batch_size):
     """Returns a batch of valid indices sampled as in Schaul et al. (2015).
diff --git a/tests/dopamine/replay_memory/prioritized_replay_buffer_test.py b/tests/dopamine/replay_memory/prioritized_replay_buffer_test.py
index db6c0e59..6049edb8 100644
--- a/tests/dopamine/replay_memory/prioritized_replay_buffer_test.py
+++ b/tests/dopamine/replay_memory/prioritized_replay_buffer_test.py
@@ -60,6 +60,20 @@ def add_blank(self, memory, action=0, reward=0.0, terminal=0, priority=1.0):
     index = (memory.cursor() - 1) % REPLAY_CAPACITY
     return index
 
+  def testAddWithAndWithoutPriority(self):
+    memory = self.create_default_memory()
+    self.assertEqual(memory.cursor(), 0)
+    zeros = np.zeros(SCREEN_SIZE)
+
+    self.add_blank(memory)
+    self.assertEqual(memory.cursor(), STACK_SIZE)
+    self.assertEqual(memory.add_count, STACK_SIZE)
+
+    # Check that the prioritized replay buffer expects an additional argument
+    # for priority.
+    with self.assertRaisesRegexp(ValueError, 'Add expects'):
+      memory.add(zeros, 0, 0, 0)
+
   def testDummyScreensAddedToNewMemory(self):
     memory = self.create_default_memory()
     index = self.add_blank(memory)