diff --git a/routes/css.cpp b/routes/css.cpp
index bb69822..50aebe4 100644
--- a/routes/css.cpp
+++ b/routes/css.cpp
@@ -134,7 +134,13 @@ static const constexpr char css[] = R"EOF(
 )EOF";
 #define CSS_LEN sizeof(css) / sizeof(css[0]) - 1
 
-constinit const uint64_t css_hash = FastHash(css, CSS_LEN, 0);
+#if __cpp_constinit
+    #define CONSTINIT constinit
+#else
+    #define CONSTINIT
+#endif
+
+CONSTINIT const uint64_t css_hash = FastHash(css, CSS_LEN, 0);
 
 void css_route(const httplib::Request& req, httplib::Response& res) {
     res.set_header("ETag", std::string(1, '"') + std::to_string(css_hash) + '"');