diff --git a/Userland/Libraries/LibJS/Runtime/Date.cpp b/Userland/Libraries/LibJS/Runtime/Date.cpp
index 7a77a8f499..873671a633 100644
--- a/Userland/Libraries/LibJS/Runtime/Date.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Date.cpp
@@ -21,6 +21,8 @@ static Crypto::SignedBigInteger const s_one_billion_bigint { 1'000'000'000 };
 static Crypto::SignedBigInteger const s_one_million_bigint { 1'000'000 };
 static Crypto::SignedBigInteger const s_one_thousand_bigint { 1'000 };
 
+Crypto::SignedBigInteger const ns_per_day_bigint { static_cast<i64>(ns_per_day) };
+
 NonnullGCPtr<Date> Date::create(Realm& realm, double date_value)
 {
     return realm.heap().allocate<Date>(realm, date_value, *realm.intrinsics().date_prototype());
diff --git a/Userland/Libraries/LibJS/Runtime/Date.h b/Userland/Libraries/LibJS/Runtime/Date.h
index 2757694c89..c1374e3ede 100644
--- a/Userland/Libraries/LibJS/Runtime/Date.h
+++ b/Userland/Libraries/LibJS/Runtime/Date.h
@@ -31,22 +31,22 @@ private:
 };
 
 // https://tc39.es/ecma262/#eqn-HoursPerDay
-constexpr double hours_per_day = 24;
+constexpr inline double hours_per_day = 24;
 // https://tc39.es/ecma262/#eqn-MinutesPerHour
-constexpr double minutes_per_hour = 60;
+constexpr inline double minutes_per_hour = 60;
 // https://tc39.es/ecma262/#eqn-SecondsPerMinute
-constexpr double seconds_per_minute = 60;
+constexpr inline double seconds_per_minute = 60;
 // https://tc39.es/ecma262/#eqn-msPerSecond
-constexpr double ms_per_second = 1'000;
+constexpr inline double ms_per_second = 1'000;
 // https://tc39.es/ecma262/#eqn-msPerMinute
-constexpr double ms_per_minute = 60'000;
+constexpr inline double ms_per_minute = 60'000;
 // https://tc39.es/ecma262/#eqn-msPerHour
-constexpr double ms_per_hour = 3'600'000;
+constexpr inline double ms_per_hour = 3'600'000;
 // https://tc39.es/ecma262/#eqn-msPerDay
-constexpr double ms_per_day = 86'400'000;
+constexpr inline double ms_per_day = 86'400'000;
 // https://tc39.es/proposal-temporal/#eqn-nsPerDay
-constexpr double ns_per_day = 86'400'000'000'000;
-static auto const ns_per_day_bigint = "86400000000000"_sbigint;
+constexpr inline double ns_per_day = 86'400'000'000'000;
+extern Crypto::SignedBigInteger const ns_per_day_bigint;
 
 u16 day_within_year(double);
 u8 date_from_time(double);