diff --git a/portal-frontend/src/app/features/notice-of-intents/edit-submission/additional-information/additional-information.component.ts b/portal-frontend/src/app/features/notice-of-intents/edit-submission/additional-information/additional-information.component.ts
index c71eac32d..6a78fd025 100644
--- a/portal-frontend/src/app/features/notice-of-intents/edit-submission/additional-information/additional-information.component.ts
+++ b/portal-frontend/src/app/features/notice-of-intents/edit-submission/additional-information/additional-information.component.ts
@@ -506,7 +506,7 @@ export class AdditionalInformationComponent extends FilesStepComponent implement
     return item.type === STRUCTURE_TYPES.PRINCIPAL_RESIDENCE || item.type === STRUCTURE_TYPES.ADDITIONAL_RESIDENCE;
   }
 
-  private addControl(area: number | null = null) {
+  private addControl(area: number | null = null): FormProposedStructure {
     const areaStr = area ? area.toString(10) : null;
     const newStructure: FormProposedStructure = { type: null, area: areaStr, id: v4() };
     this.proposedStructures.push(newStructure);