diff --git a/ansible_mitogen/connection.py b/ansible_mitogen/connection.py
index e017608e..f14576ad 100644
--- a/ansible_mitogen/connection.py
+++ b/ansible_mitogen/connection.py
@@ -914,9 +914,9 @@ class Connection(ansible.plugins.connection.ConnectionBase):
             emulate_tty=emulate_tty,
         )
 
-        stderr += 'Shared connection to %s closed.%s' % (
-            self._play_context.remote_addr,
-            ('\r\n' if emulate_tty else '\n'),
+        stderr += b'Shared connection to %s closed.%s' % (
+            self._play_context.remote_addr.encode(),
+            (b'\r\n' if emulate_tty else b'\n'),
         )
         return rc, stdout, stderr
 
diff --git a/ansible_mitogen/target.py b/ansible_mitogen/target.py
index 0e74f960..83069422 100644
--- a/ansible_mitogen/target.py
+++ b/ansible_mitogen/target.py
@@ -541,7 +541,7 @@ def exec_args(args, in_data='', chdir=None, shell=None, emulate_tty=False):
 
     if emulate_tty:
         stdout = stdout.replace(b'\n', b'\r\n')
-    return proc.returncode, stdout, stderr or ''
+    return proc.returncode, stdout, stderr or b''
 
 
 def exec_command(cmd, in_data='', chdir=None, shell=None, emulate_tty=False):
diff --git a/tests/ansible/integration/connection/exec_command.yml b/tests/ansible/integration/connection/exec_command.yml
index 6a632961..105505d1 100644
--- a/tests/ansible/integration/connection/exec_command.yml
+++ b/tests/ansible/integration/connection/exec_command.yml
@@ -15,5 +15,5 @@
   - assert:
       that:
       - out.result[0] == 0
-      - out.result[1] == "hello, world\r\n"
-      - out.result[2].startswith("Shared connection to ")
+      - out.result[1].decode() == "hello, world\r\n"
+      - out.result[2].decode().startswith("Shared connection to ")