diff --git a/docs/x509.rst b/docs/x509.rst
index afc9620..8a85561 100644
--- a/docs/x509.rst
+++ b/docs/x509.rst
@@ -275,6 +275,7 @@
 
             >>> for ext in cert.extensions:
             ...     print(ext)
+            <Extension(oid=<ObjectIdentifier(oid=2.5.29.14, name=subjectKeyIdentifier)>, critical=False, value=<SubjectKeyIdentifier(value=580184241bbc2b52944a3da510721451f5af3ac9)>)>
             <Extension(oid=<ObjectIdentifier(oid=2.5.29.19, name=basicConstraints)>, critical=True, value=<BasicConstraints(ca=True, path_length=None)>)>
 
 X.509 CSR (Certificate Signing Request) Object
@@ -576,6 +577,25 @@
     purposes indicated in the key usage extension. The object is
     iterable to obtain the list of :ref:`extended key usage OIDs <eku_oids>`.
 
+.. class:: SubjectKeyIdentifier
+
+    .. versionadded:: 0.9
+
+    The subject key identifier extension provides a means of identifying
+    certificates that contain a particular public key.
+
+    .. attribute:: digest
+
+        :type: bytes
+
+        The binary value of the identifier.
+
+    .. attribute:: hexdigest
+
+        :type: :term:`text`
+
+        The hexadecimal value of the identifier.
+
 
 Object Identifiers
 ~~~~~~~~~~~~~~~~~~