diff --git a/OpenSSL/test/test_crypto.py b/OpenSSL/test/test_crypto.py
index 4c66d6e..17a26b0 100644
--- a/OpenSSL/test/test_crypto.py
+++ b/OpenSSL/test/test_crypto.py
@@ -2062,6 +2062,9 @@
         of arguments.
         """
         self.assertRaises(TypeError, dump_privatekey)
+        # If cipher name is given, password is required.
+        self.assertRaises(
+            ValueError, dump_privatekey, FILETYPE_PEM, PKey(), "foo")
 
 
     def test_dump_privatekey_unknown_cipher(self):