diff --git a/ui-ngx/src/app/modules/home/components/widget/lib/chart/time-series-chart.ts b/ui-ngx/src/app/modules/home/components/widget/lib/chart/time-series-chart.ts
index b1928157e2..21f5f2d68c 100644
--- a/ui-ngx/src/app/modules/home/components/widget/lib/chart/time-series-chart.ts
+++ b/ui-ngx/src/app/modules/home/components/widget/lib/chart/time-series-chart.ts
@@ -661,7 +661,7 @@ export class TbTimeSeriesChart {
           }
         }
       } else if (limit.type === ValueSourceType.constant) {
-        const value = unitConvertor ? unitConvertor(limit.value) : limit.value;
+        const value = unitConvertor && isDefinedAndNotNull(limit.value) ? unitConvertor(limit.value) : limit.value;
         if (limitType === 'min') {
           yAxis.option.min = value;
         } else {