diff --git a/spec.html b/spec.html
index 4328bb0..4689f1b 100644
--- a/spec.html
+++ b/spec.html
@@ -90,6 +90,10 @@
         there is no training period for this layout.</li>
     </ol>
 
+    <p>In Windows, this layout works better with the US-International layout,
+    as that includes a true AltGr key. The regular US layout uses a Right Alt
+    key, and that can get in the way of the Layer 3 and Layer 4 symbols.</p>
+
     <h2 id="images">Images</h2>
     <h3 id="image-iso">ISO</h3>
     <svg viewBox="0 0 1200 400" width="900" height="300" role="img">