diff --git a/.circleci/config.yml b/.circleci/config.yml
index d20f72a..5e7368a 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -16,10 +16,10 @@ jobs:
           command: apt-get update && apt-get install -y ffmpeg
       - run:
           name: install python dependencies
-          command: pip install -r requirements.txt && pip install pytest
+          command: pip install -r requirements.txt && pip install pytest pytest-xdist
       - run:
           name: pytest
-          command: pytest -W ignore::FutureWarning -W ignore::DeprecationWarning -vv
+          command: pytest -W ignore::FutureWarning -W ignore::DeprecationWarning -vv --forked
       - save_cache:
           key: models-{{ checksum "spleeter/model/__init__.py" }}
           paths:
@@ -40,10 +40,10 @@ jobs:
           command: apt-get update && apt-get install -y ffmpeg
       - run:
           name: install python dependencies
-          command: pip install -r requirements.txt && pip install pytest
+          command: pip install -r requirements.txt && pip install pytest pytest-xdist
       - run:
           name: pytest
-          command: pytest -W ignore::FutureWarning -W ignore::DeprecationWarning -vv
+          command: pytest -W ignore::FutureWarning -W ignore::DeprecationWarning -vv --forked
       - save_cache:
           key: models-{{ checksum "spleeter/model/__init__.py" }}
           paths:
diff --git a/tests/test_separator.py b/tests/test_separator.py
index 5358d06..54c9c18 100644
--- a/tests/test_separator.py
+++ b/tests/test_separator.py
@@ -30,7 +30,7 @@ def test_separate(configuration, instruments):
     waveform, _ = adapter.load(TEST_AUDIO_DESCRIPTOR)
     separator = Separator(configuration)
     prediction = separator.separate(waveform)
-    assert len(prediction) == 2
+    assert len(prediction) == len(instruments)
     for instrument in instruments:
         assert instrument in prediction