diff --git a/library/core/tests/ptr.rs b/library/core/tests/ptr.rs
index 40b2b49bdbd7d..3e2956eac8753 100644
--- a/library/core/tests/ptr.rs
+++ b/library/core/tests/ptr.rs
@@ -19,6 +19,7 @@ fn test_const_from_raw_parts() {
 #[test]
 fn test() {
     unsafe {
+        #[repr(C)]
         struct Pair {
             fst: isize,
             snd: isize,