diff --git a/embassy-sync/tests/ui/sync_impl/lazy_lock_function.rs b/embassy-sync/tests/ui/sync_impl/lazy_lock_function.rs
index c6e6f7e64..35f5587c0 100644
--- a/embassy-sync/tests/ui/sync_impl/lazy_lock_function.rs
+++ b/embassy-sync/tests/ui/sync_impl/lazy_lock_function.rs
@@ -3,13 +3,9 @@ use embassy_sync::lazy_lock::LazyLock;
 fn main() {
     let x = 128u8;
     let x_ptr: *const u8 = core::ptr::addr_of!(x);
+    let closure_capturing_non_sync_variable = || unsafe { core::ptr::read(x_ptr) };
 
-    let closure_capturing_non_sync_variable = || {
-        unsafe {
-            core::ptr::read(x_ptr)
-        }
-    };
-
-    // This should fail to compile because the closure captures a non-Sync variable: x_ptr.
-    let _lazy_u8: LazyLock<u8, _> = LazyLock::new(closure_capturing_non_sync_variable);
+    check_sync(LazyLock::new(closure_capturing_non_sync_variable));
 }
+
+fn check_sync<T: Sync>(_lazy_lock: T) {}
diff --git a/embassy-sync/tests/ui/sync_impl/lazy_lock_function.stderr b/embassy-sync/tests/ui/sync_impl/lazy_lock_function.stderr
new file mode 100644
index 000000000..daf79ad28
--- /dev/null
+++ b/embassy-sync/tests/ui/sync_impl/lazy_lock_function.stderr
@@ -0,0 +1,24 @@
+error[E0277]: `*const u8` cannot be shared between threads safely
+  --> tests/ui/sync_impl/lazy_lock_function.rs:8:16
+   |
+6  |     let closure_capturing_non_sync_variable = || unsafe { core::ptr::read(x_ptr) };
+   |                                               -- within this `{closure@$DIR/tests/ui/sync_impl/lazy_lock_function.rs:6:47: 6:49}`
+7  |
+8  |     check_sync(LazyLock::new(closure_capturing_non_sync_variable));
+   |     ---------- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `*const u8` cannot be shared between threads safely
+   |     |
+   |     required by a bound introduced by this call
+   |
+   = help: within `{closure@$DIR/tests/ui/sync_impl/lazy_lock_function.rs:6:47: 6:49}`, the trait `Sync` is not implemented for `*const u8`
+   = note: required because it appears within the type `&*const u8`
+note: required because it's used within this closure
+  --> tests/ui/sync_impl/lazy_lock_function.rs:6:47
+   |
+6  |     let closure_capturing_non_sync_variable = || unsafe { core::ptr::read(x_ptr) };
+   |                                               ^^
+   = note: required for `embassy_sync::lazy_lock::LazyLock<u8, {closure@$DIR/tests/ui/sync_impl/lazy_lock_function.rs:6:47: 6:49}>` to implement `Sync`
+note: required by a bound in `check_sync`
+  --> tests/ui/sync_impl/lazy_lock_function.rs:11:18
+   |
+11 | fn check_sync<T: Sync>(_lazy_lock: T) {}
+   |                  ^^^^ required by this bound in `check_sync`
diff --git a/embassy-sync/tests/ui/sync_impl/lazy_lock_type.stderr b/embassy-sync/tests/ui/sync_impl/lazy_lock_type.stderr
new file mode 100644
index 000000000..1ccc54c7a
--- /dev/null
+++ b/embassy-sync/tests/ui/sync_impl/lazy_lock_type.stderr
@@ -0,0 +1,9 @@
+error[E0277]: `*mut u8` cannot be shared between threads safely
+ --> tests/ui/sync_impl/lazy_lock_type.rs:4:16
+  |
+4 | static GLOBAL: LazyLock<*mut u8> = LazyLock::new(|| core::ptr::null_mut());
+  |                ^^^^^^^^^^^^^^^^^ `*mut u8` cannot be shared between threads safely
+  |
+  = help: the trait `Sync` is not implemented for `*mut u8`
+  = note: required for `embassy_sync::lazy_lock::LazyLock<*mut u8>` to implement `Sync`
+  = note: shared static variables must have a type that implements `Sync`
diff --git a/embassy-sync/tests/ui/sync_impl/once_lock.stderr b/embassy-sync/tests/ui/sync_impl/once_lock.stderr
new file mode 100644
index 000000000..e2419f844
--- /dev/null
+++ b/embassy-sync/tests/ui/sync_impl/once_lock.stderr
@@ -0,0 +1,9 @@
+error[E0277]: `*mut u8` cannot be shared between threads safely
+ --> tests/ui/sync_impl/once_lock.rs:4:16
+  |
+4 | static GLOBAL: OnceLock<*mut u8> = OnceLock::new();
+  |                ^^^^^^^^^^^^^^^^^ `*mut u8` cannot be shared between threads safely
+  |
+  = help: the trait `Sync` is not implemented for `*mut u8`
+  = note: required for `embassy_sync::once_lock::OnceLock<*mut u8>` to implement `Sync`
+  = note: shared static variables must have a type that implements `Sync`