diff --git a/tests/compile-fail/validity/discriminant.rs b/tests/compile-fail/validity/discriminant.rs
new file mode 100644
index 0000000000..cdd1c02999
--- /dev/null
+++ b/tests/compile-fail/validity/discriminant.rs
@@ -0,0 +1,7 @@
+// error-pattern: type validation failed: encountered 0x02, but expected a boolean
+#[allow(enum_intrinsics_non_enums)]
+fn main() {
+    let i = 2u8;
+    // See https://github.com/rust-lang/rust/pull/89764: reading the discriminant asserts full validity.
+    std::mem::discriminant(unsafe { &*(&i as *const _ as *const bool) });
+}