diff --git a/demos/xychart.html b/demos/xychart.html
index 8cd6a64af..31fff36e8 100644
--- a/demos/xychart.html
+++ b/demos/xychart.html
@@ -67,7 +67,7 @@
       title "Basic xychart with multiple datasets"
       x-axis "Relevant categories" [category1, "category 2", category3, category4]
       y-axis Animals 0 --> 160
-      bar "dogs" [40, 20, 40, 30]
+      bar "dogs" [0, 60, 40, 30]
       bar "cats" [20, 40, 50, 30]
       bar "birds" [30, 60, 50, 30]
     </pre>
@@ -78,7 +78,7 @@
       title "Basic xychart with multiple datasets"
       x-axis "Relevant categories" [category1, "category 2", category3, category4]
       y-axis Animals 0 --> 160
-      bar "dogs" [40, 20, 40, 30]
+      bar "dogs" [0, 60, 40, 30]
       bar "cats" [20, 40, 50, 30]
       bar "birds" [30, 60, 50, 30]
     </pre>
diff --git a/packages/mermaid/src/diagrams/xychart/xychartDb.ts b/packages/mermaid/src/diagrams/xychart/xychartDb.ts
index 637477f28..b8d27e88c 100644
--- a/packages/mermaid/src/diagrams/xychart/xychartDb.ts
+++ b/packages/mermaid/src/diagrams/xychart/xychartDb.ts
@@ -137,7 +137,7 @@ function transformDataWithoutCategory(data: number[]): SimplePlotDataType {
   }
 
   if (isBandAxisData(xyChartData.xAxis)) {
-    retData = xyChartData.xAxis.categories.map((c, i) => [c, data[i]]);
+    retData = xyChartData.xAxis.categories.map((c, i) => [c, data[i] ?? 0]);
   }
 
   if (isLinearAxisData(xyChartData.xAxis)) {
@@ -148,7 +148,7 @@ function transformDataWithoutCategory(data: number[]): SimplePlotDataType {
     for (let i = min; i <= max; i += step) {
       categories.push(`${i}`);
     }
-    retData = categories.map((c, i) => [c, data[i]]);
+    retData = categories.map((c, i) => [c, data[i] ?? 0]);
   }
 
   return retData;