diff --git a/audio_separator/separator/separator.py b/audio_separator/separator/separator.py
index 9a8e42f..574166e 100644
--- a/audio_separator/separator/separator.py
+++ b/audio_separator/separator/separator.py
@@ -962,7 +962,7 @@ def _process_with_chunking(self, audio_file_path, custom_output_names=None):
                     self.model_instance.output_dir = temp_dir
 
                 try:
-                    output_files = self._separate_file(chunk_path, custom_output_names)
+                    output_files = self._separate_file(chunk_path)
 
                     # Dynamically group chunks by stem name
                     for stem_path in output_files:
diff --git a/tests/unit/test_separator_chunking.py b/tests/unit/test_separator_chunking.py
index f26ce9e..4548091 100644
--- a/tests/unit/test_separator_chunking.py
+++ b/tests/unit/test_separator_chunking.py
@@ -318,7 +318,7 @@ def test_state_restoration_after_chunking(self, mock_chunker_class):
 
         # Track state changes during _separate_file call
         state_during_processing = {}
-        def track_state(chunk_path, custom_names):
+        def track_state(chunk_path, custom_names=None):
             state_during_processing['chunk_duration'] = separator.chunk_duration
             state_during_processing['output_dir'] = separator.output_dir
             state_during_processing['model_output_dir'] = separator.model_instance.output_dir