diff --git a/src/interfaces.ts b/src/interfaces.ts
index 3b79c99bd0..42781cbdad 100644
--- a/src/interfaces.ts
+++ b/src/interfaces.ts
@@ -133,5 +133,5 @@ export interface Var {
 	initialised?: boolean;
 	hoistable?: boolean;
 	subscribable?: boolean;
-	is_reactive_dependency: boolean;
+	is_reactive_dependency?: boolean;
 }
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