diff --git a/tests/test_separator.py b/tests/test_separator.py
index 85643c1..2c244ad 100644
--- a/tests/test_separator.py
+++ b/tests/test_separator.py
@@ -32,9 +32,10 @@ MODEL_TO_INST = {
 TEST_CONFIGURATIONS = list(itertools.product(TEST_AUDIO_DESCRIPTORS, MODELS, BACKENDS))
 
 
-@pytest.mark.parametrize('configuration, instruments, backend', TEST_CONFIGURATIONS)
-def test_separate(test_file, configuration, instruments, backend):
+@pytest.mark.parametrize('test_file, configuration, backend', TEST_CONFIGURATIONS)
+def test_separate(test_file, configuration, backend):
     """ Test separation from raw data. """
+    instruments = MODEL_TO_INST[configuration]
     adapter = get_default_audio_adapter()
     waveform, _ = adapter.load(test_file)
     separator = Separator(configuration, stft_backend=backend)
@@ -51,9 +52,10 @@ def test_separate(test_file, configuration, instruments, backend):
                 assert not np.allclose(track, prediction[compared])
 
 
-@pytest.mark.parametrize('configuration, instruments, backend', TEST_CONFIGURATIONS)
-def test_separate_to_file(test_file, configuration, instruments, backend):
+@pytest.mark.parametrize('test_file, configuration, backend', TEST_CONFIGURATIONS)
+def test_separate_to_file(test_file, configuration, backend):
     """ Test file based separation. """
+    instruments = MODEL_TO_INST[configuration]
     separator = Separator(configuration, stft_backend=backend)
     basename = splitext(basename(test_file))
     with TemporaryDirectory() as directory:
@@ -66,9 +68,10 @@ def test_separate_to_file(test_file, configuration, instruments, backend):
                 '{}/{}.wav'.format(basename, instrument)))
 
 
-@pytest.mark.parametrize('configuration, instruments, backend', TEST_CONFIGURATIONS)
-def test_filename_format(test_file, configuration, instruments, backend):
+@pytest.mark.parametrize('test_file, configuration, backend', TEST_CONFIGURATIONS)
+def test_filename_format(test_file, configuration, backend):
     """ Test custom filename format. """
+    instruments = MODEL_TO_INST[configuration]
     separator = Separator(configuration, stft_backend=backend)
     basename = splitext(basename(test_file))
     with TemporaryDirectory() as directory:
@@ -82,6 +85,7 @@ def test_filename_format(test_file, configuration, instruments, backend):
                 'export/{}/{}.wav'.format(basename, instrument)))
 
 
+@pytest.mark.parametrize('test_file', TEST_AUDIO_DESCRIPTORS)
 def test_filename_conflict(test_file):
     """ Test error handling with static pattern. """
     separator = Separator(TEST_CONFIGURATIONS[0][0])