diff --git a/rust/pin-init/src/__internal.rs b/rust/pin-init/src/__internal.rs
index 914c4d1a06eb..cba53b8c3c94 100644
--- a/rust/pin-init/src/__internal.rs
+++ b/rust/pin-init/src/__internal.rs
@@ -67,6 +67,10 @@ pub unsafe fn new() -> Self {
 ///
 /// `pin-init` relies on the correctness of the helper functions defined on `PinData`.
 /// Thus, only the `#[pin_data]` can implement this trait.
+#[diagnostic::on_unimplemented(
+    message = "`{Self}` cannot be used with `pin_init!` macro",
+    note = "did you forget to add `#[pin_data]` attribute to the struct?"
+)]
 pub unsafe trait HasPinData {
     type PinData;