diff --git a/src/json.hpp.re2c b/src/json.hpp.re2c
index 4c666d92e..98f9755fb 100644
--- a/src/json.hpp.re2c
+++ b/src/json.hpp.re2c
@@ -300,7 +300,7 @@ class basic_json
     */
     friend bool operator<(const value_t lhs, const value_t rhs)
     {
-        std::array<uint8_t, 7> order = {{
+        static constexpr  std::array<uint8_t, 7> order = {{
                 0, // null
                 3, // object
                 4, // array