diff --git a/date.h b/date.h
index 81a748a..d611dbd 100644
--- a/date.h
+++ b/date.h
@@ -5165,25 +5165,25 @@ parse(std::basic_istream<CharT, Traits>& is,
         const CharT* command = nullptr;
         auto modified = CharT{};
         auto width = -1;
-        constexpr int not_a_year = 33000;
+        CONSTDATA int not_a_year = 33000;
         int Y = not_a_year;
-        constexpr int not_a_century = not_a_year / 100;
+        CONSTDATA int not_a_century = not_a_year / 100;
         int C = not_a_century;
-        constexpr int not_a_2digit_year = 100;
+        CONSTDATA int not_a_2digit_year = 100;
         int y = not_a_2digit_year;
         int m{};
         int d{};
         int j{};
-        constexpr int not_a_weekday = 7;
+        CONSTDATA int not_a_weekday = 7;
         int wd = not_a_weekday;
-        constexpr int not_a_hour_12_value = 0;
+        CONSTDATA int not_a_hour_12_value = 0;
         int I = not_a_hour_12_value;
         hours h{};
         minutes min{};
         Duration s{};
         int g = not_a_2digit_year;
         int G = not_a_year;
-        constexpr int not_a_week_num = 100;
+        CONSTDATA int not_a_week_num = 100;
         int V = not_a_week_num;
         int U = not_a_week_num;
         int W = not_a_week_num;