diff --git a/src/corelib/global/qtypes.cpp b/src/corelib/global/qtypes.cpp
index 5c3b963a922..1063f507c54 100644
--- a/src/corelib/global/qtypes.cpp
+++ b/src/corelib/global/qtypes.cpp
@@ -399,5 +399,17 @@ static_assert(sizeof(qint8) == 1, "Internal error, qint8 is misdefined");
 static_assert(sizeof(qint16)== 2, "Internal error, qint16 is misdefined");
 static_assert(sizeof(qint32) == 4, "Internal error, qint32 is misdefined");
 static_assert(sizeof(qint64) == 8, "Internal error, qint64 is misdefined");
+#ifdef QT_SUPPORTS_INT128
+static_assert(sizeof(qint128) == 16, "Internal error, qint128 is misdefined");
+#endif
+
+#ifdef QT_SUPPORTS_INT128
+// check that numeric_limits works:
+// This fails here for GCC 9, but succeeds on Clang and GCC >= 11
+// so just suppress the check for older GCC:
+#  if !defined(Q_CC_GNU_ONLY) || Q_CC_GNU >= 1100
+static_assert(std::numeric_limits<quint128>::max() == quint128(-1));
+#  endif
+#endif
 
 QT_END_NAMESPACE
diff --git a/tests/auto/corelib/global/qglobal/qglobal.c b/tests/auto/corelib/global/qglobal/qglobal.c
index abe6ec4fde0..bf6d19cb81c 100644
--- a/tests/auto/corelib/global/qglobal/qglobal.c
+++ b/tests/auto/corelib/global/qglobal/qglobal.c
@@ -3,6 +3,7 @@
 
 #include <QtCore/qglobal.h>
 #include <QtCore/qtversion.h>
+#include <QtCore/qtypes.h>
 
 #ifdef Q_COMPILER_THREAD_LOCAL
 #  include <threads.h>
@@ -44,6 +45,12 @@ void tst_GlobalTypes()
     qintptr qip;
     quintptr qup;
     Q_UNUSED(qs); Q_UNUSED(qp); Q_UNUSED(qip); Q_UNUSED(qup);
+
+#ifdef QT_SUPPORTS_INT128
+    qint128 s128;
+    quint128 u128;
+    Q_UNUSED(s128); Q_UNUSED(u128);
+#endif /* QT_SUPPORTS_INT128 */
 }
 
 /* Qt version */
diff --git a/tests/auto/corelib/global/qglobal/tst_qglobal.cpp b/tests/auto/corelib/global/qglobal/tst_qglobal.cpp
index 3d9759ff5bf..33be8fd0a27 100644
--- a/tests/auto/corelib/global/qglobal/tst_qglobal.cpp
+++ b/tests/auto/corelib/global/qglobal/tst_qglobal.cpp
@@ -422,11 +422,17 @@ void tst_QGlobal::integerForSize()
     static_assert(sizeof(QIntegerForSize<2>::Signed) == 2);
     static_assert(sizeof(QIntegerForSize<4>::Signed) == 4);
     static_assert(sizeof(QIntegerForSize<8>::Signed) == 8);
+#ifdef QT_SUPPORTS_INT128
+    static_assert(sizeof(QIntegerForSize<16>::Signed) == 16);
+#endif
 
     static_assert(sizeof(QIntegerForSize<1>::Unsigned) == 1);
     static_assert(sizeof(QIntegerForSize<2>::Unsigned) == 2);
     static_assert(sizeof(QIntegerForSize<4>::Unsigned) == 4);
     static_assert(sizeof(QIntegerForSize<8>::Unsigned) == 8);
+#ifdef QT_SUPPORTS_INT128
+    static_assert(sizeof(QIntegerForSize<16>::Unsigned) == 16);
+#endif
 }
 
 typedef QPair<const char *, const char *> stringpair;