diff --git a/compiler/rustc_index/src/vec/tests.rs b/compiler/rustc_index/src/vec/tests.rs
index 15c43c72c7b3..915d2e8bcb3f 100644
--- a/compiler/rustc_index/src/vec/tests.rs
+++ b/compiler/rustc_index/src/vec/tests.rs
@@ -1,5 +1,9 @@
 #![allow(dead_code)]
-newtype_index!(struct MyIdx { MAX = 0xFFFF_FFFA });
+
+// Allows the macro invocation below to work
+use crate as rustc_index;
+
+rustc_macros::newtype_index!(struct MyIdx { MAX = 0xFFFF_FFFA });
 
 #[test]
 fn index_size_is_optimized() {