diff --git a/reference/stream/functions/stream-set-blocking.xml b/reference/stream/functions/stream-set-blocking.xml
index d8ac7af601..5ff6759abf 100644
--- a/reference/stream/functions/stream-set-blocking.xml
+++ b/reference/stream/functions/stream-set-blocking.xml
@@ -69,6 +69,10 @@
     <function>socket_set_blocking</function> but this usage is deprecated.
    </para>
   </note>
+  <note>
+   <para>On Windows, this has no affect on local files. Non-blocking IO for local files is not supported on Windows.
+   </para>
+  </note>
  </refsect1>
 
  <refsect1 role="seealso">