diff --git a/rust/pin-init/src/lib.rs b/rust/pin-init/src/lib.rs
index 319485dc18ce..d1ed0561bb27 100644
--- a/rust/pin-init/src/lib.rs
+++ b/rust/pin-init/src/lib.rs
@@ -966,6 +966,9 @@ macro_rules! assert_pinned {
 #[cfg_attr(not(kernel), doc = "[`Arc<T>`]: alloc::alloc::sync::Arc")]
 #[cfg_attr(not(kernel), doc = "[`Box<T>`]: alloc::alloc::boxed::Box")]
 #[must_use = "An initializer must be used in order to create its value."]
+#[diagnostic::on_unimplemented(
+    message = "`{Self}` cannot be used to initialize `{T}` with error `{E}`"
+)]
 pub unsafe trait PinInit<T: ?Sized, E = Infallible>: Sized {
     /// Alias of [`PinInit::__init`].
     ///
@@ -1100,6 +1103,11 @@ unsafe fn __init(self, slot: *mut T) -> Result<(), E> {
 #[cfg_attr(not(kernel), doc = "[`Arc<T>`]: alloc::alloc::sync::Arc")]
 #[cfg_attr(not(kernel), doc = "[`Box<T>`]: alloc::alloc::boxed::Box")]
 #[must_use = "An initializer must be used in order to create its value."]
+#[diagnostic::on_unimplemented(
+    message = "`{Self}` cannot be used to movably initialize `{T}` with error `{E}`",
+    note = "if your type implements `PinInit` but not `Init`, \
+            you might be forgetting a `#[pin]` annotation on fields"
+)]
 pub unsafe trait Init<T: ?Sized, E = Infallible>: PinInit<T, E> {
     /// First initializes the value using `self` then calls the function `f` with the initialized
     /// value.