diff --git a/src/cryptography/x509/extensions.py b/src/cryptography/x509/extensions.py
index 7979ccb..ac70cc1 100644
--- a/src/cryptography/x509/extensions.py
+++ b/src/cryptography/x509/extensions.py
@@ -270,6 +270,9 @@
     def __ne__(self, other):
         return not self == other
 
+    def __getitem__(self, idx):
+        return self._descriptions[idx]
+
 
 class AccessDescription(object):
     def __init__(self, access_method, access_location):
diff --git a/tests/test_x509_ext.py b/tests/test_x509_ext.py
index cfca579..92e6e1a 100644
--- a/tests/test_x509_ext.py
+++ b/tests/test_x509_ext.py
@@ -2210,6 +2210,32 @@
         assert aia != aia2
         assert aia != object()
 
+    def test_indexing(self):
+        aia = x509.AuthorityInformationAccess([
+            x509.AccessDescription(
+                AuthorityInformationAccessOID.OCSP,
+                x509.UniformResourceIdentifier(u"http://ocsp.domain.com")
+            ),
+            x509.AccessDescription(
+                AuthorityInformationAccessOID.CA_ISSUERS,
+                x509.UniformResourceIdentifier(u"http://domain.com/ca.crt")
+            ),
+            x509.AccessDescription(
+                AuthorityInformationAccessOID.OCSP,
+                x509.UniformResourceIdentifier(u"http://ocsp2.domain.com")
+            ),
+            x509.AccessDescription(
+                AuthorityInformationAccessOID.OCSP,
+                x509.UniformResourceIdentifier(u"http://ocsp3.domain.com")
+            ),
+            x509.AccessDescription(
+                AuthorityInformationAccessOID.OCSP,
+                x509.UniformResourceIdentifier(u"http://ocsp4.domain.com")
+            ),
+        ])
+        assert aia[-1] == aia[4]
+        assert aia[2:6:2] == [aia[2], aia[4]]
+
 
 @pytest.mark.requires_backend_interface(interface=RSABackend)
 @pytest.mark.requires_backend_interface(interface=X509Backend)