diff --git a/crates/macro-support/src/parser.rs b/crates/macro-support/src/parser.rs
index 46c76a1ef21..a10d823b3b3 100644
--- a/crates/macro-support/src/parser.rs
+++ b/crates/macro-support/src/parser.rs
@@ -1418,6 +1418,11 @@ impl MacroParse<&ClassMarker> for &mut syn::ImplItemFn {
             FunctionPosition::Impl { self_ty: class },
         )?;
         let method_kind = if opts.constructor().is_some() {
+            if function.r#async {
+                self.attrs.push(syn::parse_quote! {
+                    #[deprecated(note = "constructors cannot be async")]
+                });
+            }
             ast::MethodKind::Constructor
         } else {
             let is_static = method_self.is_none();