diff --git a/OpenSSL/crypto/x509.c b/OpenSSL/crypto/x509.c
index 4f29b97..9ee28e8 100644
--- a/OpenSSL/crypto/x509.c
+++ b/OpenSSL/crypto/x509.c
@@ -543,7 +543,7 @@
         PyErr_SetString(PyExc_ValueError, "Undefined signature algorithm");
         return NULL;
     }
-    return PyString_FromString(OBJ_nid2ln(nid));
+    return PyBytes_FromString(OBJ_nid2ln(nid));
 }
 
 
diff --git a/OpenSSL/test/test_crypto.py b/OpenSSL/test/test_crypto.py
index 1fcb543..55c42f1 100644
--- a/OpenSSL/test/test_crypto.py
+++ b/OpenSSL/test/test_crypto.py
@@ -1486,7 +1486,7 @@
         the algorithm used to sign the certificate.
         """
         cert = load_certificate(FILETYPE_PEM, self.pemData)
-        self.assertEqual(cert.get_signature_algorithm(), "sha1WithRSAEncryption")
+        self.assertEqual(cert.get_signature_algorithm(), b("sha1WithRSAEncryption"))
 
 
     def test_get_undefined_signature_algorithm(self):