diff --git a/GDJS/Runtime/types/project-data.d.ts b/GDJS/Runtime/types/project-data.d.ts
index 322b3101e46..d92fb9114e9 100644
--- a/GDJS/Runtime/types/project-data.d.ts
+++ b/GDJS/Runtime/types/project-data.d.ts
@@ -100,7 +100,7 @@ declare interface EventsFunctionsExtensionData {
 }
 
 declare interface LayoutAndExtensionsData extends LayoutData {
-  usedExtensionsWithVariablesData: EventsFunctionsExtensionData[];
+  usedExtensionsWithVariablesData?: ?EventsFunctionsExtensionData[];
 }
 
 declare interface EventsBasedObjectData {