diff --git a/src/gui/painting/qfixed_p.h b/src/gui/painting/qfixed_p.h
index cc7dbff4013..cabfc6529cd 100644
--- a/src/gui/painting/qfixed_p.h
+++ b/src/gui/painting/qfixed_p.h
@@ -51,11 +51,19 @@
 // We mean it.
 //
 
+// clang-format off
+
 #include <QtGui/private/qtguiglobal_p.h>
 #include "QtCore/qdebug.h"
 #include "QtCore/qpoint.h"
+#if defined(Q_OS_WIN)
+#include <qt_windows.h> // to suppress min, max macros.
+#endif
+#include <QtCore/private/qnumeric_p.h>
 #include "QtCore/qsize.h"
 
+// clang-format on
+
 QT_BEGIN_NAMESPACE
 
 struct QFixed {
@@ -182,6 +190,14 @@ Q_DECL_CONSTEXPR inline bool operator<(int i, const QFixed &f) { return i * 64 <
 Q_DECL_CONSTEXPR inline bool operator>(const QFixed &f, int i) { return f.value() > i * 64; }
 Q_DECL_CONSTEXPR inline bool operator>(int i, const QFixed &f) { return i * 64 > f.value(); }
 
+inline bool qAddOverflow(QFixed v1, QFixed v2, QFixed *r)
+{
+    int val;
+    bool result = add_overflow(v1.value(), v2.value(), &val);
+    r->setValue(val);
+    return result;
+}
+
 #ifndef QT_NO_DEBUG_STREAM
 inline QDebug &operator<<(QDebug &dbg, const QFixed &f)
 { return dbg << f.toReal(); }
diff --git a/src/gui/text/qtextlayout.cpp b/src/gui/text/qtextlayout.cpp
index ab591700458..d19322aa1b2 100644
--- a/src/gui/text/qtextlayout.cpp
+++ b/src/gui/text/qtextlayout.cpp
@@ -2163,11 +2163,14 @@ found:
         eng->maxWidth = qMax(eng->maxWidth, line.textWidth);
     } else {
         eng->minWidth = qMax(eng->minWidth, lbh.minw);
-        eng->maxWidth += line.textWidth;
+        if (qAddOverflow(eng->maxWidth, line.textWidth, &eng->maxWidth))
+            eng->maxWidth = QFIXED_MAX;
     }
 
-    if (line.textWidth > 0 && item < eng->layoutData->items.size())
-        eng->maxWidth += lbh.spaceData.textWidth;
+    if (line.textWidth > 0 && item < eng->layoutData->items.size()) {
+        if (qAddOverflow(eng->maxWidth, lbh.spaceData.textWidth, &eng->maxWidth))
+            eng->maxWidth = QFIXED_MAX;
+    }
 
     line.textWidth += trailingSpace;
     if (lbh.spaceData.length) {
diff --git a/src/plugins/platforms/windows/windows.pri b/src/plugins/platforms/windows/windows.pri
index 95ba961df12..6bb4fafd735 100644
--- a/src/plugins/platforms/windows/windows.pri
+++ b/src/plugins/platforms/windows/windows.pri
@@ -17,7 +17,7 @@ QMAKE_USE_PRIVATE += \
     user32 \
     winmm
 
-DEFINES *= QT_NO_CAST_FROM_ASCII QT_NO_FOREACH
+DEFINES *= QT_NO_CAST_FROM_ASCII QT_NO_FOREACH NOMINMAX
 
 SOURCES += \
     $$PWD/qwindowswindow.cpp \