diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index a56450a3573..02848bcffb2 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -893,6 +893,7 @@
         masked,
         match_beginning_vert,
         match_default_bindings,
+        matches_macro,
         maxnumf32,
         maxnumf64,
         may_dangle,
diff --git a/library/core/src/macros/mod.rs b/library/core/src/macros/mod.rs
index 34247c05845..c20ca69a1c6 100644
--- a/library/core/src/macros/mod.rs
+++ b/library/core/src/macros/mod.rs
@@ -338,6 +338,7 @@ macro_rules! debug_assert_ne {
 /// ```
 #[macro_export]
 #[stable(feature = "matches_macro", since = "1.42.0")]
+#[cfg_attr(not(test), rustc_diagnostic_item = "matches_macro")]
 macro_rules! matches {
     ($expression:expr, $(|)? $( $pattern:pat_param )|+ $( if $guard: expr )? $(,)?) => {
         match $expression {