@@ -242,7 +242,9 @@ static int config_props(AVFilterLink *outlink)

 fail:

     av_log(NULL, AV_LOG_ERROR,

-           "Error when evaluating the expression '%s'\n", expr);

+           "Error when evaluating the expression '%s'.\n"

+           "Maybe the expression for out_w:'%s' or for out_h:'%s' is self-referencing.\n",

+           expr, scale->w_expr, scale->h_expr);

     return ret;

 }