diff --git a/tests/fail/reading_half_a_pointer.rs b/tests/fail/reading_half_a_pointer.rs
index 7dd98eab78..feac30b83c 100644
--- a/tests/fail/reading_half_a_pointer.rs
+++ b/tests/fail/reading_half_a_pointer.rs
@@ -1,7 +1,7 @@
 #![allow(dead_code)]
 
 // We use packed structs to get around alignment restrictions
-#[repr(packed)]
+#[repr(C, packed)]
 struct Data {
     pad: u8,
     ptr: &'static i32,
diff --git a/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.rs b/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.rs
index 8459c64ed2..06dd97deed 100644
--- a/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.rs
+++ b/tests/fail/unaligned_pointers/field_requires_parent_struct_alignment2.rs
@@ -7,7 +7,7 @@ pub struct Aligned {
     _pad: [u8; 11],
     packed: Packed,
 }
-#[repr(packed)]
+#[repr(C, packed)]
 #[derive(Default, Copy, Clone)]
 pub struct Packed {
     _pad: [u8; 5],