--- a/js/src/frontend/Parser.cpp
+++ b/js/src/frontend/Parser.cpp
@@ -5042,16 +5042,30 @@ Parser<FullParseHandler>::exportDeclarat
                 return null();
             break;
           case TOK_CLASS:
             kid = classDefinition(YieldIsKeyword, ClassStatement, AllowDefaultName);
             if (!kid)
                 return null();
             break;
           default: {
+            if (tt == TOK_NAME && tokenStream.currentName() == context->names().async) {
+                TokenKind nextSameLine = TOK_EOF;
+                if (!tokenStream.peekTokenSameLine(&nextSameLine))
+                    return null();
+
+                if (nextSameLine == TOK_FUNCTION) {
+                    tokenStream.consumeKnownToken(nextSameLine);
+                    kid = functionStmt(YieldIsName, AllowDefaultName, AsyncFunction);
+                    if (!kid)
+                        return null();
+                    break;
+                }
+            }
+
             tokenStream.ungetToken();
             RootedPropertyName name(context, context->names().starDefaultStar);
             nameNode = newName(name);
             if (!nameNode)
                 return null();
             if (!noteDeclaredName(name, DeclarationKind::Const, pos()))
                 return null();
             kid = assignExpr(InAllowed, YieldIsKeyword, TripledotProhibited);