diff --git a/docs/extensions/index.md b/docs/extensions/index.md
index 90b72c4805..d2f1b09537 100644
--- a/docs/extensions/index.md
+++ b/docs/extensions/index.md
@@ -133,7 +133,7 @@ const char* custom_op_library_filename = "/path/to/the/onnxruntime-extensions/sh
 Ort::SessionOptions session_options;
 
 // Register Extensions custom ops with the session options.
-Ort::ThrowOnError(Ort::GetApi().RegisterCustomOpsLibrary_V2(static_cast<OrtSessionOptions*(session_options),
+Ort::ThrowOnError(Ort::GetApi().RegisterCustomOpsLibrary_V2(static_cast<OrtSessionOptions*>(session_options),
                                                             custom_op_library_filename));
 
 // Create a session.