diff --git a/src/cryptography/x509.py b/src/cryptography/x509.py
index d43b8f0..bcda721 100644
--- a/src/cryptography/x509.py
+++ b/src/cryptography/x509.py
@@ -1834,12 +1834,14 @@
             extension = Extension(
                 OID_SUBJECT_KEY_IDENTIFIER, critical, extension
             )
-        elif isinstance(extension, InhibitAnyPolicy):
-            extension = Extension(OID_INHIBIT_ANY_POLICY, critical, extension)
         elif isinstance(extension, CRLDistributionPoints):
             extension = Extension(
                 OID_CRL_DISTRIBUTION_POINTS, critical, extension
             )
+        elif isinstance(extension, IssuerAlternativeName):
+            extension = Extension(
+                OID_ISSUER_ALTERNATIVE_NAME, critical, extension
+            )
         else:
             raise NotImplementedError('Unsupported X.509 extension.')
 
diff --git a/tests/hazmat/backends/test_openssl.py b/tests/hazmat/backends/test_openssl.py
index 051827a..8f559c8 100644
--- a/tests/hazmat/backends/test_openssl.py
+++ b/tests/hazmat/backends/test_openssl.py
@@ -529,7 +529,7 @@
         ).not_valid_after(
             datetime.datetime(2020, 1, 1)
         ).add_extension(
-            x509.InhibitAnyPolicy(0), False
+            x509.IssuerAlternativeName([x509.DNSName(u"crypto.io")]), False
         )
 
         with pytest.raises(NotImplementedError):