diff --git a/documentation/docs/07-misc/04-custom-elements.md b/documentation/docs/07-misc/04-custom-elements.md
index a8e0c81763..8dbcdd25a3 100644
--- a/documentation/docs/07-misc/04-custom-elements.md
+++ b/documentation/docs/07-misc/04-custom-elements.md
@@ -114,6 +114,8 @@ When constructing a custom element, you can tailor several aspects by defining `
 ...
 ```
 
+> [!NOTE] While Typescript is supported in the `extend` function is subject to the same limitations of the script tags: you need to set `lang="ts"` on one of the scripts AND you can only use [erasable syntax](https://www.typescriptlang.org/tsconfig/#erasableSyntaxOnly) in it.
+
 ## Caveats and limitations
 
 Custom elements can be a useful way to package components for consumption in a non-Svelte app, as they will work with vanilla HTML and JavaScript as well as [most frameworks](https://custom-elements-everywhere.com/). There are, however, some important differences to be aware of: