diff --git a/compiler/rustc_symbol_mangling/src/errors.rs b/compiler/rustc_symbol_mangling/src/errors.rs
index 4872dfa2653a6..242997365a892 100644
--- a/compiler/rustc_symbol_mangling/src/errors.rs
+++ b/compiler/rustc_symbol_mangling/src/errors.rs
@@ -4,7 +4,7 @@ use rustc_macros::SessionDiagnostic;
 use rustc_span::Span;
 
 #[derive(SessionDiagnostic)]
-#[error(symbol_mangling::invalid_symbol_name)]
+#[diag(symbol_mangling::invalid_symbol_name)]
 pub struct InvalidSymbolName {
     #[primary_span]
     pub span: Span,
@@ -12,7 +12,7 @@ pub struct InvalidSymbolName {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(symbol_mangling::invalid_trait_item)]
+#[diag(symbol_mangling::invalid_trait_item)]
 pub struct InvalidTraitItem {
     #[primary_span]
     pub span: Span,
@@ -20,7 +20,7 @@ pub struct InvalidTraitItem {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(symbol_mangling::alt_invalid_trait_item)]
+#[diag(symbol_mangling::alt_invalid_trait_item)]
 pub struct AltInvalidTraitItem {
     #[primary_span]
     pub span: Span,
@@ -28,7 +28,7 @@ pub struct AltInvalidTraitItem {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(symbol_mangling::invalid_def_path)]
+#[diag(symbol_mangling::invalid_def_path)]
 pub struct InvalidDefPath {
     #[primary_span]
     pub span: Span,