diff --git a/TC1/http_server/web/index.html b/TC1/http_server/web/index.html
index c6d1662..1565b9e 100644
--- a/TC1/http_server/web/index.html
+++ b/TC1/http_server/web/index.html
@@ -1079,7 +1079,7 @@
         var w_v_t = (17.1 * (power.p_count - power.p_count_1_day_ago)) / 1000 / 36000;
         w_v_t = w_v_t < 0 ? 0 : w_v_t;
         w_t.innerHTML = w_v_t.toFixed(3);
-        var w_v_y = (17.1 * power.p_count_1_day_ago - power.p_count_2_days_ago) / 1000 / 36000;
+        var w_v_y = (17.1 * (power.p_count_1_day_ago - power.p_count_2_days_ago)) / 1000 / 36000;
         w_v_y = w_v_y < 0 ? 0 : w_v_y;
         w_y.innerHTML = w_v_y.toFixed(3);
         if (power.child_lock_enabled == 1) {