diff --git a/docs/x509/reference.rst b/docs/x509/reference.rst
index dace8c1..f53eae0 100644
--- a/docs/x509/reference.rst
+++ b/docs/x509/reference.rst
@@ -1695,6 +1695,27 @@
 
         :type: int
 
+.. class:: CRLNumber(crl_number)
+
+    .. versionadded:: 1.2
+
+    The CRL number is a non-critical CRL extension that conveys a
+    monotonically increasing sequence number for a given CRL scope and
+    CRL issuer. This extension allows users to easily determine when a
+    particular CRL supersedes another CRL. :rfc:`5280` requires that this
+    extension be present in conforming CRLs.
+
+    .. attribute:: oid
+
+        :type: :class:`ObjectIdentifier`
+
+        Returns
+        :attr:`~cryptography.x509.oid.ExtensionOID.CRL_NUMBER`.
+
+    .. attribute:: crl_number
+
+        :type: int
+
 .. class:: CertificatePolicies(policies)
 
     .. versionadded:: 0.9