diff --git a/platypush/backend/__init__.py b/platypush/backend/__init__.py
index 3722a9c4..2b161f70 100644
--- a/platypush/backend/__init__.py
+++ b/platypush/backend/__init__.py
@@ -216,7 +216,7 @@ class Backend(Thread, EventGenerator, ExtensionWithManifest):
                 raise KeyError()
         except KeyError:
             self.logger.warning((
-                "Backend {} does not implement send_message " +
+                "Backend {} does not implement send_message "
                 "and the fallback Redis backend isn't configured"
             ).format(self.__class__.__name__))
             return
diff --git a/platypush/message/event/__init__.py b/platypush/message/event/__init__.py
index 7a972c60..8bd0ed98 100644
--- a/platypush/message/event/__init__.py
+++ b/platypush/message/event/__init__.py
@@ -1,7 +1,6 @@
 import copy
 import hashlib
 import json
-import random
 import re
 import time
 import uuid
diff --git a/setup.py b/setup.py
index adeae5ff..45f37333 100755
--- a/setup.py
+++ b/setup.py
@@ -205,7 +205,7 @@ setup(
         # Support for Z-Wave
         'zwave': ['python-openzwave'],
         # Support for Mozilla DeepSpeech speech-to-text engine
-        'deepspeech': ['deepspeech', 'numpy','sounddevice'],
+        'deepspeech': ['deepspeech', 'numpy', 'sounddevice'],
         # Support for PicoVoice hotword detection engine
         'picovoice-hotword': ['pvporcupine'],
         # Support for PicoVoice speech-to-text engine
@@ -215,7 +215,7 @@ setup(
         # Support for Linode integration
         'linode': ['linode_api4'],
         # Support for QR codes
-        'qrcode': ['numpy','qrcode[pil]', 'Pillow', 'pyzbar'],
+        'qrcode': ['numpy', 'qrcode[pil]', 'Pillow', 'pyzbar'],
         # Support for Tensorflow
         'tensorflow': ['numpy', 'tensorflow>=2.0', 'keras', 'pandas'],
         # Support for Samsung TizenOS-based smart TVs