diff --git a/src/corelib/time/qdatetime.cpp b/src/corelib/time/qdatetime.cpp
index faf3fe38de..369b04c751 100644
--- a/src/corelib/time/qdatetime.cpp
+++ b/src/corelib/time/qdatetime.cpp
@@ -1,7 +1,7 @@
 /****************************************************************************
 **
 ** Copyright (C) 2021 The Qt Company Ltd.
-** Copyright (C) 2016 Intel Corporation.
+** Copyright (C) 2021 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -3454,6 +3454,10 @@ inline qint64 QDateTimePrivate::zoneMSecsToEpochMSecs(qint64 zoneMSecs, const QT
 */
 QDateTime::QDateTime() noexcept
 {
+#if QT_VERSION >= QT_VERSION_CHECK(7,0,0) || QT_POINTER_SIZE == 8
+    static_assert(sizeof(ShortData) == sizeof(qint64));
+    static_assert(sizeof(Data) == sizeof(qint64));
+#endif
 }
 
 /*!
diff --git a/src/corelib/time/qdatetime.h b/src/corelib/time/qdatetime.h
index bc8c09b1e9..80227afde2 100644
--- a/src/corelib/time/qdatetime.h
+++ b/src/corelib/time/qdatetime.h
@@ -1,7 +1,7 @@
 /****************************************************************************
 **
-** Copyright (C) 2020 The Qt Company Ltd.
-** Copyright (C) 2016 Intel Corporation.
+** Copyright (C) 2021 The Qt Company Ltd.
+** Copyright (C) 2021 Intel Corporation.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the QtCore module of the Qt Toolkit.
@@ -240,8 +240,12 @@ class Q_CORE_EXPORT QDateTime
 #if Q_BYTE_ORDER == Q_LITTLE_ENDIAN
         quintptr status : 8;
 #endif
+#if QT_VERSION >= QT_VERSION_CHECK(7,0,0)
+        qint64 msecs : 56;
+#else
         // note: this is only 24 bits on 32-bit systems...
         qintptr msecs : sizeof(void *) * 8 - 8;
+#endif
 
 #if Q_BYTE_ORDER == Q_BIG_ENDIAN
         quintptr status : 8;