diff --git a/api/src/engine/models/result/line-chart-result.model.ts b/api/src/engine/models/result/line-chart-result.model.ts
index ccedd1c25186e6e60b138f55b38a2403a846a333..85ea4ff66e9780a1cb01de9ea68621b6486e9de5 100644
--- a/api/src/engine/models/result/line-chart-result.model.ts
+++ b/api/src/engine/models/result/line-chart-result.model.ts
@@ -43,10 +43,10 @@ export class LineChartResult extends Result {
   @Field()
   name: string;
 
-  @Field(() => ChartAxis)
+  @Field(() => ChartAxis, { nullable: true })
   xAxis?: ChartAxis;
 
-  @Field(() => ChartAxis)
+  @Field(() => ChartAxis, { nullable: true })
   yAxis?: ChartAxis;
 
   @Field(() => [LineResult])