diff --git a/lib/instructor/adapters/anthropic.ex b/lib/instructor/adapters/anthropic.ex
index 83a210e..acaecbf 100644
--- a/lib/instructor/adapters/anthropic.ex
+++ b/lib/instructor/adapters/anthropic.ex
@@ -189,7 +189,7 @@ defmodule Instructor.Adapters.Anthropic do
 
   defp config(base_config) do
     default_config = [
-      api_url: "https://api.anthropic.com/",
+      api_url: "https://api.anthropic.com",
       api_key: System.get_env("ANTHROPIC_API_KEY"),
       http_options: [receive_timeout: 60_000]
     ]