diff --git a/OpenSSL/rand/rand.c b/OpenSSL/rand/rand.c
index 8c23015..fabf805 100644
--- a/OpenSSL/rand/rand.c
+++ b/OpenSSL/rand/rand.c
@@ -45,7 +45,7 @@
     int size;
     double entropy;
 
-    if (!PyArg_ParseTuple(args, "s#d:add", &buf, &size, &entropy))
+    if (!PyArg_ParseTuple(args, BYTESTRING_FMT "#d:add", &buf, &size, &entropy))
         return NULL;
 
     RAND_add(buf, size, entropy);
@@ -67,7 +67,7 @@
     char *buf;
     int size;
 
-    if (!PyArg_ParseTuple(args, "s#:seed", &buf, &size))
+    if (!PyArg_ParseTuple(args, BYTESTRING_FMT "#:seed", &buf, &size))
         return NULL;
 
     RAND_seed(buf, size);
diff --git a/OpenSSL/test/test_rand.py b/OpenSSL/test/test_rand.py
index c6717e9..a785168 100644
--- a/OpenSSL/test/test_rand.py
+++ b/OpenSSL/test/test_rand.py
@@ -8,7 +8,7 @@
 import os
 import stat
 
-from OpenSSL.test.util import TestCase
+from OpenSSL.test.util import TestCase, b
 from OpenSSL import rand
 
 
@@ -46,16 +46,16 @@
         type C{str} and C{int}, L{OpenSSL.rand.add} raises L{TypeError}.
         """
         self.assertRaises(TypeError, rand.add)
-        self.assertRaises(TypeError, rand.add, "foo", None)
+        self.assertRaises(TypeError, rand.add, b("foo"), None)
         self.assertRaises(TypeError, rand.add, None, 3)
-        self.assertRaises(TypeError, rand.add, "foo", 3, None)
+        self.assertRaises(TypeError, rand.add, b("foo"), 3, None)
 
 
     def test_add(self):
         """
         L{OpenSSL.rand.add} adds entropy to the PRNG.
         """
-        rand.add('hamburger', 3)
+        rand.add(b('hamburger'), 3)
 
 
     def test_seed_wrong_args(self):
@@ -65,14 +65,14 @@
         """
         self.assertRaises(TypeError, rand.seed)
         self.assertRaises(TypeError, rand.seed, None)
-        self.assertRaises(TypeError, rand.seed, "foo", None)
+        self.assertRaises(TypeError, rand.seed, b("foo"), None)
 
 
     def test_seed(self):
         """
         L{OpenSSL.rand.seed} adds entropy to the PRNG.
         """
-        rand.seed('milk shake')
+        rand.seed(b('milk shake'))
 
 
     def test_status_wrong_args(self):