@@ -123,6 +123,7 @@ static int config_input(AVFilterLink *inlink)

     double var_values[VARS_NB], res;

     char *expr;

     int ret;

+    int i;

     s->hsub = desc->log2_chroma_w;

     s->vsub = desc->log2_chroma_h;

@@ -139,7 +140,7 @@ static int config_input(AVFilterLink *inlink)

     var_values[VAR_W] = NAN;

     var_values[VAR_T] = NAN;

-    for (int i = 0; i <= NUM_EXPR_EVALS; i++) {

+    for (i = 0; i <= NUM_EXPR_EVALS; i++) {

         /* evaluate expressions, fail on last iteration */

         if ((ret = av_expr_parse_and_eval(&res, (expr = s->x_expr),

                                           var_names, var_values,