diff --git a/src/webui/www/public/scripts/misc.js b/src/webui/www/public/scripts/misc.js
index 7087f8281..645353127 100644
--- a/src/webui/www/public/scripts/misc.js
+++ b/src/webui/www/public/scripts/misc.js
@@ -38,11 +38,11 @@ function friendlyDuration(seconds) {
     if (minutes < 60)
         return "QBT_TR(%1m)QBT_TR".replace("%1", parseInt(minutes));
     var hours = minutes / 60;
-    minutes = minutes - hours * 60;
+    minutes = minutes % 60;
     if (hours < 24)
         return "QBT_TR(%1h %2m)QBT_TR".replace("%1", parseInt(hours)).replace("%2", parseInt(minutes))
     var days = hours / 24;
-    hours = hours - days * 24;
+    hours = hours % 24;
     if (days < 100)
         return "QBT_TR(%1d %2h)QBT_TR".replace("%1", parseInt(days)).replace("%2", parseInt(hours))
     return "∞";