diff --git a/mycroft/audio/services/__init__.py b/mycroft/audio/services/__init__.py
index 503030e855..c30bf95e99 100644
--- a/mycroft/audio/services/__init__.py
+++ b/mycroft/audio/services/__init__.py
@@ -15,7 +15,7 @@
 from abc import ABCMeta, abstractmethod
 
 
-class AudioBackend:
+class AudioBackend(metaclass=ABCMeta):
     """
         Base class for all audio backend implementations.
 
@@ -23,7 +23,6 @@ class AudioBackend:
             config: configuration dict for the instance
             bus:    Mycroft messagebus emitter
     """
-    __metaclass__ = ABCMeta
 
     def __init__(self, config, bus):
         self._track_start_callback = None
@@ -115,7 +114,6 @@ class AudioBackend:
         """
         pass
 
-    @abstractmethod
     def seek_forward(self, seconds=1):
         """
             Skip X seconds
@@ -125,7 +123,6 @@ class AudioBackend:
         """
         pass
 
-    @abstractmethod
     def seek_backward(self, seconds=1):
         """
             Rewind X seconds
diff --git a/mycroft/stt/__init__.py b/mycroft/stt/__init__.py
index 0a8ba35994..ef0865397e 100644
--- a/mycroft/stt/__init__.py
+++ b/mycroft/stt/__init__.py
@@ -25,9 +25,8 @@ from mycroft.configuration import Configuration
 from mycroft.util.log import LOG
 
 
-class STT:
-    __metaclass__ = ABCMeta
-
+class STT(metaclass=ABCMeta):
+    """ STT Base class, all  STT backends derives from this one. """
     def __init__(self):
         config_core = Configuration.get()
         self.lang = str(self.init_language(config_core))
@@ -50,24 +49,19 @@ class STT:
         pass
 
 
-class TokenSTT(STT):
-    __metaclass__ = ABCMeta
-
+class TokenSTT(STT, metaclass=ABCMeta):
     def __init__(self):
         super(TokenSTT, self).__init__()
         self.token = str(self.credential.get("token"))
 
 
-class GoogleJsonSTT(STT):
-    __metaclass__ = ABCMeta
-
+class GoogleJsonSTT(STT, metaclass=ABCMeta):
     def __init__(self):
         super(GoogleJsonSTT, self).__init__()
         self.json_credentials = json.dumps(self.credential.get("json"))
 
 
-class BasicSTT(STT):
-    __metaclass__ = ABCMeta
+class BasicSTT(STT, metaclass=ABCMeta):
 
     def __init__(self):
         super(BasicSTT, self).__init__()
@@ -75,8 +69,7 @@ class BasicSTT(STT):
         self.password = str(self.credential.get("password"))
 
 
-class KeySTT(STT):
-    __metaclass__ = ABCMeta
+class KeySTT(STT, metaclass=ABCMeta):
 
     def __init__(self):
         super(KeySTT, self).__init__()
@@ -169,11 +162,10 @@ class DeepSpeechServerSTT(STT):
         return response.text
 
 
-class StreamThread(Thread):
+class StreamThread(Thread, metaclass=ABCMeta):
     """
         ABC class to be used with StreamingSTT class implementations.
     """
-    __metaclass__ = ABCMeta
 
     def __init__(self, queue, language):
         super().__init__()
@@ -197,12 +189,10 @@ class StreamThread(Thread):
         pass
 
 
-class StreamingSTT(STT):
+class StreamingSTT(STT, metaclass=ABCMeta):
     """
         ABC class for threaded streaming STT implemenations.
     """
-    __metaclass__ = ABCMeta
-
     def __init__(self):
         super().__init__()
         self.stream = None
diff --git a/mycroft/tts/__init__.py b/mycroft/tts/__init__.py
index 43c26bf7fc..4cb7db55a8 100644
--- a/mycroft/tts/__init__.py
+++ b/mycroft/tts/__init__.py
@@ -141,7 +141,7 @@ class PlaybackThread(Thread):
         self.clear_queue()
 
 
-class TTS:
+class TTS(metaclass=ABCMeta):
     """
     TTS abstract class to be implemented by all TTS engines.
 
@@ -155,8 +155,6 @@ class TTS:
         phonetic_spelling (bool): Whether to spell certain words phonetically
         ssml_tags (list): Supported ssml properties. Ex. ['speak', 'prosody']
     """
-    __metaclass__ = ABCMeta
-
     def __init__(self, lang, config, validator, audio_ext='wav',
                  phonetic_spelling=True, ssml_tags=None):
         super(TTS, self).__init__()
@@ -395,15 +393,13 @@ class TTS:
         self.playback.join()
 
 
-class TTSValidator:
+class TTSValidator(metaclass=ABCMeta):
     """
     TTS Validator abstract class to be implemented by all TTS engines.
 
     It exposes and implements ``validate(tts)`` function as a template to
     validate the TTS engines.
     """
-    __metaclass__ = ABCMeta
-
     def __init__(self, tts):
         self.tts = tts