diff --git a/src/cryptography/hazmat/backends/openssl/backend.py b/src/cryptography/hazmat/backends/openssl/backend.py
index 38fe077..e8b0322 100644
--- a/src/cryptography/hazmat/backends/openssl/backend.py
+++ b/src/cryptography/hazmat/backends/openssl/backend.py
@@ -1453,16 +1453,17 @@
         if not isinstance(algorithm, hashes.HashAlgorithm):
             raise TypeError('Algorithm must be a registered hash algorithm.')
 
-        if isinstance(private_key, _DSAPrivateKey):
-            raise NotImplementedError(
-                "CRL signatures aren't implemented for DSA"
-                " keys at this time."
-            )
-        if isinstance(private_key, _EllipticCurvePrivateKey):
-            raise NotImplementedError(
-                "CRL signatures aren't implemented for EC"
-                " keys at this time."
-            )
+        if self._lib.OPENSSL_VERSION_NUMBER <= 0x10001000:
+            if isinstance(private_key, _DSAPrivateKey):
+                raise NotImplementedError(
+                    "CRL signatures aren't implemented for DSA"
+                    " keys on OpenSSL versions less than 1.0.1."
+                )
+            if isinstance(private_key, _EllipticCurvePrivateKey):
+                raise NotImplementedError(
+                    "CRL signatures aren't implemented for EC"
+                    " keys on OpenSSL versions less than 1.0.1."
+                )
 
         evp_md = self._lib.EVP_get_digestbyname(
             algorithm.name.encode('ascii')
diff --git a/tests/hazmat/backends/test_openssl.py b/tests/hazmat/backends/test_openssl.py
index c0e9d28..ad2daf7 100644
--- a/tests/hazmat/backends/test_openssl.py
+++ b/tests/hazmat/backends/test_openssl.py
@@ -558,6 +558,43 @@
         with pytest.raises(TypeError):
             backend.create_x509_crl(object(), private_key, hashes.SHA256())
 
+    @pytest.mark.skipif(
+        backend._lib.OPENSSL_VERSION_NUMBER >= 0x10001000,
+        reason="Requires an older OpenSSL. Must be < 1.0.1"
+    )
+    def test_sign_with_dsa_private_key_is_unsupported(self):
+        private_key = DSA_KEY_2048.private_key(backend)
+        builder = x509.CertificateRevocationListBuilder()
+        builder = builder.issuer_name(
+            x509.Name([x509.NameAttribute(x509.NameOID.COUNTRY_NAME, u'US')])
+        ).last_update(
+            datetime.datetime(2002, 1, 1, 12, 1)
+        ).next_update(
+            datetime.datetime(2032, 1, 1, 12, 1)
+        )
+
+        with pytest.raises(NotImplementedError):
+            builder.sign(private_key, hashes.SHA1(), backend)
+
+    @pytest.mark.skipif(
+        backend._lib.OPENSSL_VERSION_NUMBER >= 0x10001000,
+        reason="Requires an older OpenSSL. Must be < 1.0.1"
+    )
+    def test_sign_with_ec_private_key_is_unsupported(self):
+        _skip_curve_unsupported(backend, ec.SECP256R1())
+        private_key = ec.generate_private_key(ec.SECP256R1(), backend)
+        builder = x509.CertificateRevocationListBuilder()
+        builder = builder.issuer_name(
+            x509.Name([x509.NameAttribute(x509.NameOID.COUNTRY_NAME, u'US')])
+        ).last_update(
+            datetime.datetime(2002, 1, 1, 12, 1)
+        ).next_update(
+            datetime.datetime(2032, 1, 1, 12, 1)
+        )
+
+        with pytest.raises(NotImplementedError):
+            builder.sign(private_key, hashes.SHA512(), backend)
+
 
 class TestOpenSSLCreateRevokedCertificate(object):
     def test_invalid_builder(self):
diff --git a/tests/test_x509_crlbuilder.py b/tests/test_x509_crlbuilder.py
index 763a647..32a0748 100644
--- a/tests/test_x509_crlbuilder.py
+++ b/tests/test_x509_crlbuilder.py
@@ -308,8 +308,23 @@
 
     @pytest.mark.requires_backend_interface(interface=DSABackend)
     @pytest.mark.requires_backend_interface(interface=X509Backend)
-    def test_sign_dsa_key_unsupported(self, backend):
+    def test_sign_dsa_key(self, backend):
+        if backend._lib.OPENSSL_VERSION_NUMBER < 0x10001000:
+            pytest.skip("Requires a newer OpenSSL. Must be >= 1.0.1")
         private_key = DSA_KEY_2048.private_key(backend)
+        invalidity_date = x509.InvalidityDate(
+            datetime.datetime(2002, 1, 1, 0, 0)
+        )
+        ian = x509.IssuerAlternativeName([
+            x509.UniformResourceIdentifier(u"https://cryptography.io"),
+        ])
+        revoked_cert0 = x509.RevokedCertificateBuilder().serial_number(
+            2
+        ).revocation_date(
+            datetime.datetime(2012, 1, 1, 1, 1)
+        ).add_extension(
+            invalidity_date, False
+        ).build(backend)
         last_update = datetime.datetime(2002, 1, 1, 12, 1)
         next_update = datetime.datetime(2030, 1, 1, 12, 1)
         builder = x509.CertificateRevocationListBuilder().issuer_name(
@@ -320,16 +335,43 @@
             last_update
         ).next_update(
             next_update
+        ).add_revoked_certificate(
+            revoked_cert0
+        ).add_extension(
+            ian, False
         )
 
-        with pytest.raises(NotImplementedError):
-            builder.sign(private_key, hashes.SHA256(), backend)
+        crl = builder.sign(private_key, hashes.SHA256(), backend)
+        assert crl.extensions.get_extension_for_class(
+            x509.IssuerAlternativeName
+        ).value == ian
+        assert crl[0].serial_number == revoked_cert0.serial_number
+        assert crl[0].revocation_date == revoked_cert0.revocation_date
+        assert len(crl[0].extensions) == 1
+        ext = crl[0].extensions.get_extension_for_class(x509.InvalidityDate)
+        assert ext.critical is False
+        assert ext.value == invalidity_date
 
     @pytest.mark.requires_backend_interface(interface=EllipticCurveBackend)
     @pytest.mark.requires_backend_interface(interface=X509Backend)
     def test_sign_ec_key_unsupported(self, backend):
+        if backend._lib.OPENSSL_VERSION_NUMBER < 0x10001000:
+            pytest.skip("Requires a newer OpenSSL. Must be >= 1.0.1")
         _skip_curve_unsupported(backend, ec.SECP256R1())
         private_key = ec.generate_private_key(ec.SECP256R1(), backend)
+        invalidity_date = x509.InvalidityDate(
+            datetime.datetime(2002, 1, 1, 0, 0)
+        )
+        ian = x509.IssuerAlternativeName([
+            x509.UniformResourceIdentifier(u"https://cryptography.io"),
+        ])
+        revoked_cert0 = x509.RevokedCertificateBuilder().serial_number(
+            2
+        ).revocation_date(
+            datetime.datetime(2012, 1, 1, 1, 1)
+        ).add_extension(
+            invalidity_date, False
+        ).build(backend)
         last_update = datetime.datetime(2002, 1, 1, 12, 1)
         next_update = datetime.datetime(2030, 1, 1, 12, 1)
         builder = x509.CertificateRevocationListBuilder().issuer_name(
@@ -340,10 +382,22 @@
             last_update
         ).next_update(
             next_update
+        ).add_revoked_certificate(
+            revoked_cert0
+        ).add_extension(
+            ian, False
         )
 
-        with pytest.raises(NotImplementedError):
-            builder.sign(private_key, hashes.SHA256(), backend)
+        crl = builder.sign(private_key, hashes.SHA256(), backend)
+        assert crl.extensions.get_extension_for_class(
+            x509.IssuerAlternativeName
+        ).value == ian
+        assert crl[0].serial_number == revoked_cert0.serial_number
+        assert crl[0].revocation_date == revoked_cert0.revocation_date
+        assert len(crl[0].extensions) == 1
+        ext = crl[0].extensions.get_extension_for_class(x509.InvalidityDate)
+        assert ext.critical is False
+        assert ext.value == invalidity_date
 
     @pytest.mark.requires_backend_interface(interface=RSABackend)
     @pytest.mark.requires_backend_interface(interface=X509Backend)