diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index b80ecbc9c65..62d0deb2d3a 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -510,7 +510,7 @@ fn literal_from_str(&mut self, s: &str) -> Result<Literal<Self::Span, Self::Symb
 
     fn emit_diagnostic(&mut self, diagnostic: Diagnostic<Self::Span>) {
         let message = rustc_errors::DiagnosticMessage::from(diagnostic.message);
-        let mut diag: DiagnosticBuilder<'_, rustc_errors::ErrorGuaranteed> =
+        let mut diag: DiagnosticBuilder<'_, ()> =
             DiagnosticBuilder::new(&self.sess().dcx, diagnostic.level.to_internal(), message);
         diag.span(MultiSpan::from_spans(diagnostic.spans));
         for child in diagnostic.children {