diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index a05f0d69d54..8c13aff577d 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -3264,6 +3264,14 @@ void QGuiApplicationPrivate::processExposeEvent(QWindowSystemInterfacePrivate::E
     const bool wasExposed = p->exposed;
     p->exposed = e->isExposed && window->screen();
 
+    // We expect that the platform plugins send DevicePixelRatioChange events.
+    // As a fail-safe make a final check here to make sure the cached DPR value is
+    // always up to date before sending the expose event.
+    const bool dprWasChanged = QWindowPrivate::get(window)->updateDevicePixelRatio();
+    if (dprWasChanged)
+        qWarning() << "The cached device pixel ratio value was stale on window expose. "
+                   << "Please file a QTBUG which explains how to reproduce.";
+
     // We treat expose events for an already exposed window as paint events
     if (wasExposed && p->exposed && shouldSynthesizePaintEvents) {
         QPaintEvent paintEvent(e->region);
diff --git a/src/gui/kernel/qwindow.cpp b/src/gui/kernel/qwindow.cpp
index 3c9194cb6ed..0aeb1514057 100644
--- a/src/gui/kernel/qwindow.cpp
+++ b/src/gui/kernel/qwindow.cpp
@@ -1359,8 +1359,9 @@ qreal QWindow::devicePixelRatio() const
 /*
     Updates the cached devicePixelRatio value by polling for a new value.
     Sends QEvent::DevicePixelRatioChange to the window if the DPR has changed.
+    Returns true if the DPR was changed.
 */
-void QWindowPrivate::updateDevicePixelRatio()
+bool QWindowPrivate::updateDevicePixelRatio()
 {
     Q_Q(QWindow);
 
@@ -1371,11 +1372,12 @@ void QWindowPrivate::updateDevicePixelRatio()
         platformWindow->devicePixelRatio() * QHighDpiScaling::factor(q) : q->screen()->devicePixelRatio();
 
     if (newDevicePixelRatio == devicePixelRatio)
-        return;
+        return false;
 
     devicePixelRatio = newDevicePixelRatio;
     QEvent dprChangeEvent(QEvent::DevicePixelRatioChange);
     QGuiApplication::sendEvent(q, &dprChangeEvent);
+    return true;
 }
 
 Qt::WindowState QWindowPrivate::effectiveState(Qt::WindowStates state)
diff --git a/src/gui/kernel/qwindow_p.h b/src/gui/kernel/qwindow_p.h
index 96beb17becf..7b1aad4838c 100644
--- a/src/gui/kernel/qwindow_p.h
+++ b/src/gui/kernel/qwindow_p.h
@@ -89,7 +89,7 @@ public:
     void setAutomaticPositionAndResizeEnabled(bool a)
     { positionAutomatic = resizeAutomatic = a; }
 
-    void updateDevicePixelRatio();
+    bool updateDevicePixelRatio();
 
     static QWindowPrivate *get(QWindow *window) { return window->d_func(); }