diff --git a/TTS/tts/configs/speedy_speech_config.py b/TTS/tts/configs/speedy_speech_config.py
index 6007b741..c4bfa991 100644
--- a/TTS/tts/configs/speedy_speech_config.py
+++ b/TTS/tts/configs/speedy_speech_config.py
@@ -1,8 +1,8 @@
 from dataclasses import dataclass, field
 from typing import List
 
-from TTS.tts.models.forward_tts import ForwardTTSArgs
 from TTS.tts.configs.shared_configs import BaseTTSConfig
+from TTS.tts.models.forward_tts import ForwardTTSArgs
 
 
 @dataclass
diff --git a/TTS/tts/datasets/dataset.py b/TTS/tts/datasets/dataset.py
index bfe0d778..04314bab 100644
--- a/TTS/tts/datasets/dataset.py
+++ b/TTS/tts/datasets/dataset.py
@@ -419,6 +419,7 @@ class TTSDataset(Dataset):
                 d_vectors = [self.d_vector_mapping[w]["embedding"] for w in wav_files_names]
             else:
                 d_vectors = None
+
             # get numerical speaker ids from speaker names
             if self.speaker_id_mapping:
                 speaker_ids = [self.speaker_id_mapping[sn] for sn in batch["speaker_name"]]
diff --git a/TTS/tts/models/align_tts.py b/TTS/tts/models/align_tts.py
index 8e001630..eef06f12 100644
--- a/TTS/tts/models/align_tts.py
+++ b/TTS/tts/models/align_tts.py
@@ -100,7 +100,7 @@ class AlignTTS(BaseTTS):
 
     # pylint: disable=dangerous-default-value
 
-    def __init__(self, config: Coqpit, speaker_manager: SpeakerManager=None):
+    def __init__(self, config: Coqpit, speaker_manager: SpeakerManager = None):
 
         super().__init__(config)
         self.speaker_manager = speaker_manager
diff --git a/TTS/tts/models/base_tacotron.py b/TTS/tts/models/base_tacotron.py
index d0cc81cc..ca8f3bb9 100644
--- a/TTS/tts/models/base_tacotron.py
+++ b/TTS/tts/models/base_tacotron.py
@@ -1,6 +1,6 @@
 import copy
 from abc import abstractmethod
-from typing import Dict, List
+from typing import Dict
 
 import torch
 from coqpit import Coqpit
diff --git a/TTS/tts/models/tacotron.py b/TTS/tts/models/tacotron.py
index 9ed5dc91..4e46d252 100644
--- a/TTS/tts/models/tacotron.py
+++ b/TTS/tts/models/tacotron.py
@@ -258,10 +258,10 @@ class Tacotron(BaseTacotron):
                 stop_targets.float(),
                 stop_target_lengths,
                 mel_lengths,
-                outputs["decoder_outputs_backward"].float(),
+                None if outputs["decoder_outputs_backward"] is None else outputs["decoder_outputs_backward"].float(),
                 outputs["alignments"].float(),
                 alignment_lengths,
-                outputs["alignments_backward"].float(),
+                None if outputs["alignments_backward"] is None else outputs["alignments_backward"].float(),
                 text_lengths,
             )
 
diff --git a/TTS/tts/models/tacotron2.py b/TTS/tts/models/tacotron2.py
index 4307c90e..ead3bf2b 100644
--- a/TTS/tts/models/tacotron2.py
+++ b/TTS/tts/models/tacotron2.py
@@ -1,6 +1,7 @@
 # coding: utf-8
 
 from typing import Dict
+
 import torch
 from coqpit import Coqpit
 from torch import nn
@@ -237,7 +238,7 @@ class Tacotron2(BaseTacotron):
         }
         return outputs
 
-    def train_step(self, batch:Dict, criterion:torch.nn.Module):
+    def train_step(self, batch: Dict, criterion: torch.nn.Module):
         """A single training step. Forward pass and loss computation.
 
         Args:
diff --git a/TTS/tts/models/vits.py b/TTS/tts/models/vits.py
index 3b7df353..a449a575 100644
--- a/TTS/tts/models/vits.py
+++ b/TTS/tts/models/vits.py
@@ -216,7 +216,7 @@ class Vits(BaseTTS):
 
     # pylint: disable=dangerous-default-value
 
-    def __init__(self, config: Coqpit, speaker_manager: SpeakerManager=None):
+    def __init__(self, config: Coqpit, speaker_manager: SpeakerManager = None):
 
         super().__init__(config)