diff --git a/docs/x509.rst b/docs/x509.rst
index 035fa87..5f36a92 100644
--- a/docs/x509.rst
+++ b/docs/x509.rst
@@ -452,7 +452,12 @@
     .. versionadded:: 0.9
 
     This corresponds to a uniform resource identifier.  For example,
-    ``https://cryptography.io``.
+    ``https://cryptography.io``. The URI is parsed and IDNA decoded (see
+    :rfc:`5895`).
+
+    .. note::
+
+        URIs that do not contain ``://`` in them will not be decoded.
 
     .. attribute:: value