diff --git a/dbus/dbus-sysdeps-util-win.c b/dbus/dbus-sysdeps-util-win.c
index 5aad2a86..fc356908 100644
--- a/dbus/dbus-sysdeps-util-win.c
+++ b/dbus/dbus-sysdeps-util-win.c
@@ -1399,7 +1399,8 @@ _dbus_command_for_pid (unsigned long  pid,
                        int            max_len,
                        DBusError     *error)
 {
-  // FIXME
+  dbus_set_error (error, DBUS_ERROR_NOT_SUPPORTED,
+                  "_dbus_command_for_pid() not implemented on Windows");
   return FALSE;
 }