diff --git a/tests/__init__.py b/tests/__init__.py
index 2b07004f..45aee23a 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -7,8 +7,8 @@ from TTS.utils.generic_utils import get_cuda
 def get_device_id():
     use_cuda, _ = get_cuda()
     if use_cuda:
-        if 'CUDA_VISIBLE_DEVICES' in os.environ and os.environ['CUDA_VISIBLE_DEVICES'] != "":
-            GPU_ID = os.environ['CUDA_VISIBLE_DEVICES'].split(',')[0]
+        if "CUDA_VISIBLE_DEVICES" in os.environ and os.environ["CUDA_VISIBLE_DEVICES"] != "":
+            GPU_ID = os.environ["CUDA_VISIBLE_DEVICES"].split(",")[0]
         else:
             GPU_ID = "0"
     else: