--- a/dbus/dbus-sysdeps-unix.c
+++ b/dbus/dbus-sysdeps-unix.c
@@ -1617,6 +1627,12 @@
   if (bytes_written < 0 && errno == EINTR)
     goto again;
 
+  /* sendmsg() only accepts domain == PF_UNIX*/
+#if defined(HAVE_CMSGCRED)
+  if (bytes_written < 0 && errno == EINVAL)
+    bytes_written = send (server_fd, buf, 1, 0);
+#endif
+
   if (bytes_written < 0)
     {
       dbus_set_error (error, _dbus_error_from_errno (errno),
@@ -1753,8 +1769,12 @@
     }
 
 #if defined(HAVE_CMSGCRED) || defined(LOCAL_CREDS)
-  if (cmsg.hdr.cmsg_len < CMSG_LEN (sizeof (struct cmsgcred))
-                 || cmsg.hdr.cmsg_type != SCM_CREDS)
+  /* Special case for a zero credentials byte written */
+  if (bytes_read == 1 && buf == '\0')
+    {
+    }
+  else if (cmsg.hdr.cmsg_len < CMSG_LEN (sizeof (struct cmsgcred))
+      || cmsg.hdr.cmsg_type != SCM_CREDS)
     {
       dbus_set_error (error, DBUS_ERROR_FAILED,
                       "Message from recvmsg() was not SCM_CREDS");