diff --git a/main.go b/main.go
index 48b155f..3838a21 100644
--- a/main.go
+++ b/main.go
@@ -277,7 +277,7 @@ func AvgChart(f *excelize.File, worksheetName string, location string, avgCpuCol
 			Font: excelize.Font{
 				Color: "000000",
 			},
-			Maximum: *yMaxValue,
+			Maximum: &yMaxValue,
 		},
 		Dimension: excelize.ChartDimension{
 			Height: 500,