diff --git a/src/compiler/preprocess/types.ts b/src/compiler/preprocess/types.ts
index 94007371cc..4ac441b5e6 100644
--- a/src/compiler/preprocess/types.ts
+++ b/src/compiler/preprocess/types.ts
@@ -1,5 +1,8 @@
 import { Location } from 'locate-character';
 
+/**
+ * @internal
+ */
 export interface Source {
 	source: string;
 	get_location: (search: number) => Location;