diff --git a/rag/llm/rerank_model.py b/rag/llm/rerank_model.py
index 4dac44f2b3..d9a4a74059 100644
--- a/rag/llm/rerank_model.py
+++ b/rag/llm/rerank_model.py
@@ -196,10 +196,11 @@ class OpenAI_APIRerank(Base):
     _FACTORY_NAME = "OpenAI-API-Compatible"
 
     def __init__(self, key, model_name, base_url):
-        if base_url.find("/rerank") == -1:
-            self.base_url = urljoin(base_url, "/rerank")
+        normalized_base_url = (base_url or "").strip()
+        if "/rerank" in normalized_base_url:
+            self.base_url = normalized_base_url.rstrip("/")
         else:
-            self.base_url = base_url
+            self.base_url = urljoin(f"{normalized_base_url.rstrip('/')}/", "rerank").rstrip("/")
         self.headers = {"Content-Type": "application/json", "Authorization": f"Bearer {key}"}
         self.model_name = model_name.split("___")[0]