diff --git a/oslo_rootwrap/daemon.py b/oslo_rootwrap/daemon.py
index 20de185..5409dfd 100644
--- a/oslo_rootwrap/daemon.py
+++ b/oslo_rootwrap/daemon.py
@@ -21,6 +21,7 @@ from multiprocessing import managers
 import os
 import shutil
 import signal
+import six
 import stat
 import sys
 import tempfile
@@ -52,7 +53,12 @@ class RootwrapClass(object):
             stdin=subprocess.PIPE,
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE)
+        if six.PY3 and stdin is not None:
+            stdin = os.fsencode(stdin)
         out, err = obj.communicate(stdin)
+        if six.PY3:
+            out = os.fsdecode(out)
+            err = os.fsdecode(err)
         return obj.returncode, out, err
 
     def shutdown(self):
diff --git a/oslo_rootwrap/tests/test_functional.py b/oslo_rootwrap/tests/test_functional.py
index 7013d85..2201d82 100644
--- a/oslo_rootwrap/tests/test_functional.py
+++ b/oslo_rootwrap/tests/test_functional.py
@@ -59,17 +59,29 @@ sh: CommandFilter, /bin/sh, root
 id: CommandFilter, /usr/bin/id, nobody
 """)
 
-    def test_run_once(self):
+    def _test_run_once(self, expect_byte=True):
         code, out, err = self.execute(['echo', 'teststr'])
         self.assertEqual(0, code)
-        self.assertEqual(b'teststr\n', out)
-        self.assertEqual(b'', err)
+        if expect_byte:
+            expect_out = b'teststr\n'
+            expect_err = b''
+        else:
+            expect_out = 'teststr\n'
+            expect_err = ''
+        self.assertEqual(expect_out, out)
+        self.assertEqual(expect_err, err)
 
-    def test_run_with_stdin(self):
+    def _test_run_with_stdin(self, expect_byte=True):
         code, out, err = self.execute(['cat'], stdin=b'teststr')
         self.assertEqual(0, code)
-        self.assertEqual(b'teststr', out)
-        self.assertEqual(b'', err)
+        if expect_byte:
+            expect_out = b'teststr'
+            expect_err = b''
+        else:
+            expect_out = 'teststr'
+            expect_err = ''
+        self.assertEqual(expect_out, out)
+        self.assertEqual(expect_err, err)
 
     def test_run_as(self):
         if os.getuid() != 0:
@@ -106,6 +118,12 @@ class RootwrapTest(_FunctionalBase, testtools.TestCase):
                        content.text_content(err.decode('utf-8', 'replace')))
         return proc.returncode, out, err
 
+    def test_run_once(self):
+        self._test_run_once(expect_byte=True)
+
+    def test_run_with_stdin(self):
+        self._test_run_with_stdin(expect_byte=True)
+
 
 class RootwrapDaemonTest(_FunctionalBase, testtools.TestCase):
     def assert_unpatched(self):
@@ -159,6 +177,12 @@ class RootwrapDaemonTest(_FunctionalBase, testtools.TestCase):
 
         self.execute = self.client.execute
 
+    def test_run_once(self):
+        self._test_run_once(expect_byte=False)
+
+    def test_run_with_stdin(self):
+        self._test_run_with_stdin(expect_byte=False)
+
     def test_error_propagation(self):
         self.assertRaises(wrapper.NoFilterMatched, self.execute, ['other'])
 
@@ -200,8 +224,8 @@ class RootwrapDaemonTest(_FunctionalBase, testtools.TestCase):
             raise self._thread_res  # Python 3 will even provide nice traceback
         code, out, err = self._thread_res
         self.assertEqual(0, code)
-        self.assertEqual(b'OK\n', out)
-        self.assertEqual(b'', err)
+        self.assertEqual('OK\n', out)
+        self.assertEqual('', err)
 
     @contextlib.contextmanager
     def _test_daemon_cleanup(self):