diff --git a/src/test/ui/issues/issue-43398.rs b/src/test/ui/issues/issue-43398.rs
new file mode 100644
index 0000000000000000000000000000000000000000..ae52e8f3f6b43d1f300bbc0d30dd40bc64013ace
--- /dev/null
+++ b/src/test/ui/issues/issue-43398.rs
@@ -0,0 +1,15 @@
+// run-pass
+
+#![feature(core_intrinsics)]
+#![feature(repr128)]
+
+#[repr(i128)]
+enum Big { A, B }
+
+fn main() {
+    unsafe {
+        println!("{} {:?}",
+            std::intrinsics::discriminant_value(&Big::A),
+            std::mem::discriminant(&Big::B));
+    }
+}