diff --git a/rag/nlp/__init__.py b/rag/nlp/__init__.py
index 2aaf98aab0..eb529f68b5 100644
--- a/rag/nlp/__init__.py
+++ b/rag/nlp/__init__.py
@@ -466,7 +466,7 @@ def binary_search(arr, target):
                 jj = binary_search(levels[ii], j)
                 if jj < 0:
                     continue
-                if jj > cks[-1][-1]:
+                if levels[ii][jj] > cks[-1][-1]:
                     cks[-1].pop(-1)
                 cks[-1].append(levels[ii][jj])
             for ii in cks[-1]: