diff --git a/libcpp/init.c b/libcpp/init.c
index f77dc26a003..7987798afbe 100644
--- a/libcpp/init.c
+++ b/libcpp/init.c
@@ -542,7 +542,7 @@ cpp_init_builtins (cpp_reader *pfile, int hosted)
     {
       if (CPP_OPTION (pfile, lang) == CLK_CXX20
 	  || CPP_OPTION (pfile, lang) == CLK_GNUCXX20)
-	_cpp_define_builtin (pfile, "__cplusplus 201709L");
+	_cpp_define_builtin (pfile, "__cplusplus 202002L");
       else if (CPP_OPTION (pfile, lang) == CLK_CXX17
 	  || CPP_OPTION (pfile, lang) == CLK_GNUCXX17)
 	_cpp_define_builtin (pfile, "__cplusplus 201703L");