diff --git a/rag/llm/rerank_model.py b/rag/llm/rerank_model.py
index a638375f6..de6efb87b 100644
--- a/rag/llm/rerank_model.py
+++ b/rag/llm/rerank_model.py
@@ -358,7 +358,7 @@ class OpenAI_APIRerank(Base):
         max_rank = np.max(rank)
 
         # Avoid division by zero if all ranks are identical
-        if max_rank - min_rank != 0:
+        if np.isclose(min_rank, max_rank, atol=1e-3):
             rank = (rank - min_rank) / (max_rank - min_rank)
         else:
             rank = np.zeros_like(rank)