diff --git a/test/test_rb.py b/test/test_rb.py
index c95bcfdf936..74bce8d770d 100644
--- a/test/test_rb.py
+++ b/test/test_rb.py
@@ -65,7 +65,7 @@
 )
 @pytest.mark.parametrize("writer", [writers.RoundRobinWriter])
 @pytest.mark.parametrize("storage", [ListStorage, LazyTensorStorage, LazyMemmapStorage])
-@pytest.mark.parametrize("size", [3, 100])
+@pytest.mark.parametrize("size", [3, 5, 100])
 class TestPrototypeBuffers:
     def _get_rb(self, rb_type, size, sampler, writer, storage):
 
@@ -124,6 +124,26 @@ def test_add(self, rb_type, sampler, writer, storage, size):
         else:
             assert (s == data).all()
 
+    def test_cursor_position(self, rb_type, sampler, writer, storage, size):
+        storage = storage(size)
+        writer = writer()
+        writer.register_storage(storage)
+        batch1 = self._get_data(rb_type, size=5)
+        writer.extend(batch1)
+
+        # Added less data than storage max size
+        if size > 5:
+            assert writer._cursor == 5
+        # Added more data than storage max size
+        elif size < 5:
+            assert writer._cursor == 5 - size
+        # Added as data as storage max size
+        else:
+            assert writer._cursor == 0
+            batch2 = self._get_data(rb_type, size=size - 1)
+            writer.extend(batch2)
+            assert writer._cursor == size - 1
+
     def test_extend(self, rb_type, sampler, writer, storage, size):
         torch.manual_seed(0)
         rb = self._get_rb(
@@ -342,7 +362,7 @@ def test_rb_prototype_trajectories(stack):
         (TensorDictPrioritizedReplayBuffer, LazyMemmapStorage),
     ],
 )
-@pytest.mark.parametrize("size", [3, 100])
+@pytest.mark.parametrize("size", [3, 5, 100])
 @pytest.mark.parametrize("prefetch", [0])
 class TestBuffers:
     _default_params_rb = {}
@@ -404,6 +424,25 @@ def _get_data(self, rbtype, size):
             raise NotImplementedError(rbtype)
         return data
 
+    def test_cursor_position2(self, rbtype, storage, size, prefetch):
+        torch.manual_seed(0)
+        rb = self._get_rb(rbtype, storage=storage, size=size, prefetch=prefetch)
+        batch1 = self._get_data(rbtype, size=5)
+        rb.extend(batch1)
+
+        # Added less data than storage max size
+        if size > 5:
+            assert rb._cursor == 5
+        # Added more data than storage max size
+        elif size < 5:
+            assert rb._cursor == 5 - size
+        # Added as data as storage max size
+        else:
+            assert rb._cursor == 0
+            batch2 = self._get_data(rbtype, size=size - 1)
+            rb.extend(batch2)
+            assert rb._cursor == size - 1
+
     def test_add(self, rbtype, storage, size, prefetch):
         torch.manual_seed(0)
         rb = self._get_rb(rbtype, storage=storage, size=size, prefetch=prefetch)
diff --git a/torchrl/data/replay_buffers/replay_buffers.py b/torchrl/data/replay_buffers/replay_buffers.py
index 9dccba7ad07..053384e6bb8 100644
--- a/torchrl/data/replay_buffers/replay_buffers.py
+++ b/torchrl/data/replay_buffers/replay_buffers.py
@@ -195,37 +195,15 @@ def extend(self, data: Sequence[Any]):
         if not len(data):
             raise Exception("extending with empty data is not supported")
         with self._replay_lock:
-            cur_size = len(self._storage)
             batch_size = len(data)
-            # storage = self._storage
-            # cursor = self._cursor
-            if cur_size + batch_size <= self._capacity:
-                index = np.arange(cur_size, cur_size + batch_size)
-                # self._storage += data
-                self._cursor = (self._cursor + batch_size) % self._capacity
-            elif cur_size < self._capacity:
-                d = self._capacity - cur_size
-                index = np.empty(batch_size, dtype=np.int64)
-                index[:d] = np.arange(cur_size, self._capacity)
-                index[d:] = np.arange(batch_size - d)
-                # storage += data[:d]
-                # for i, v in enumerate(data[d:]):
-                #     storage[i] = v
-                self._cursor = batch_size - d
-            elif self._cursor + batch_size <= self._capacity:
+            if self._cursor + batch_size <= self._capacity:
                 index = np.arange(self._cursor, self._cursor + batch_size)
-                # for i, v in enumerate(data):
-                #     storage[cursor + i] = v
                 self._cursor = (self._cursor + batch_size) % self._capacity
             else:
                 d = self._capacity - self._cursor
                 index = np.empty(batch_size, dtype=np.int64)
                 index[:d] = np.arange(self._cursor, self._capacity)
                 index[d:] = np.arange(batch_size - d)
-                # for i, v in enumerate(data[:d]):
-                #     storage[cursor + i] = v
-                # for i, v in enumerate(data[d:]):
-                #     storage[i] = v
                 self._cursor = batch_size - d
             # storage must convert the data to the appropriate format if needed
             self._storage[index] = data
diff --git a/torchrl/data/replay_buffers/writers.py b/torchrl/data/replay_buffers/writers.py
index 88657e1fcba..f058dd32f2d 100644
--- a/torchrl/data/replay_buffers/writers.py
+++ b/torchrl/data/replay_buffers/writers.py
@@ -46,21 +46,12 @@ def extend(self, data: Sequence) -> torch.Tensor:
         if cur_size + batch_size <= self._storage.max_size:
             index = np.arange(cur_size, cur_size + batch_size)
             self._cursor = (self._cursor + batch_size) % self._storage.max_size
-        elif cur_size < self._storage.max_size:
+        else:
             d = self._storage.max_size - cur_size
             index = np.empty(batch_size, dtype=np.int64)
             index[:d] = np.arange(cur_size, self._storage.max_size)
             index[d:] = np.arange(batch_size - d)
             self._cursor = batch_size - d
-        elif self._cursor + batch_size <= self._storage.max_size:
-            index = np.arange(self._cursor, self._cursor + batch_size)
-            self._cursor = (self._cursor + batch_size) % self._storage.max_size
-        else:
-            d = self._storage.max_size - self._cursor
-            index = np.empty(batch_size, dtype=np.int64)
-            index[:d] = np.arange(self._cursor, self._storage.max_size)
-            index[d:] = np.arange(batch_size - d)
-            self._cursor = batch_size - d
         # storage must convert the data to the appropriate format if needed
         self._storage[index] = data
         return index