diff --git a/docs/design_docs/segcore/segment_growing.md b/docs/design_docs/segcore/segment_growing.md
index 2be0f7699d..c3f8ad7da4 100644
--- a/docs/design_docs/segcore/segment_growing.md
+++ b/docs/design_docs/segcore/segment_growing.md
@@ -20,7 +20,7 @@ During a search, each 'chunk' will be searched, and the search results will be s
 
 Growing Segment also implements small batch index for vectors. The parameters of small batch index are preset in `segcore config`
 
-When `metric type` is specified in the schema, the default parameters will build index for each chunk to accelerate query
+When `metric type` is specified in the schema, the default parameters will build an index for each chunk to accelerate query
 
 ## SegmentGrowingImpl internal