diff --git a/runtime/datamate-python/app/module/annotation/service/editor.py b/runtime/datamate-python/app/module/annotation/service/editor.py
index 26fb4a6..1c6fda4 100644
--- a/runtime/datamate-python/app/module/annotation/service/editor.py
+++ b/runtime/datamate-python/app/module/annotation/service/editor.py
@@ -546,6 +546,7 @@ class AnnotationEditorService:
         segment_annotation_keys: set[str],
     ) -> Tuple[List[SegmentInfo], List[Tuple[Optional[Dict[str, Any]], str, str, int, int]]]:
         splitter = AnnotationTextSplitter(max_chars=self.SEGMENT_THRESHOLD)
+        segments: List[SegmentInfo] = []
         segment_contexts: List[Tuple[Optional[Dict[str, Any]], str, str, int, int]] = []
         segment_cursor = 0