diff --git a/modules/misc/lua/vlc.c b/modules/misc/lua/vlc.c
index ee0b057ef254a56885f06bab1b67e5e34e136e98..dc8daacf14dea46e4d81c3b9ad0b04db3befc4c6 100644
--- a/modules/misc/lua/vlc.c
+++ b/modules/misc/lua/vlc.c
@@ -687,6 +687,7 @@ static int vlc_sd_probe_Open( vlc_object_t *obj )
             lua_getglobal( L, "descriptor" );
             if( !lua_isfunction( L, lua_gettop( L ) ) || lua_pcall( L, 0, 1, 0 ) )
             {
+                msg_Warn( probe, "No 'descriptor' function in '%s'", psz_filename );
                 lua_pop( L, 1 );
                 if( !( psz_longname = strdup( *ppsz_file ) ) )
                 {