diff --git a/src/cryptography/hazmat/backends/openssl/x509.py b/src/cryptography/hazmat/backends/openssl/x509.py
index b342cd8..4699a7a 100644
--- a/src/cryptography/hazmat/backends/openssl/x509.py
+++ b/src/cryptography/hazmat/backends/openssl/x509.py
@@ -864,14 +864,13 @@
     def _revoked_certificates(self):
         revoked = self._backend._lib.X509_CRL_get_REVOKED(self._x509_crl)
         revoked_list = []
-        if revoked != self._backend._ffi.NULL:
-            for i in range(len(self)):
-                r = self._backend._lib.sk_X509_REVOKED_value(revoked, i)
-                self._backend.openssl_assert(r != self._backend._ffi.NULL)
-                revoked_certificate = _RevokedCertificate(
-                    self._backend, self, r
-                )
-                revoked_list.append(revoked_certificate)
+        for i in range(len(self)):
+            r = self._backend._lib.sk_X509_REVOKED_value(revoked, i)
+            self._backend.openssl_assert(r != self._backend._ffi.NULL)
+            revoked_certificate = _RevokedCertificate(
+                self._backend, self, r
+            )
+            revoked_list.append(revoked_certificate)
 
         return revoked_list