diff --git a/klipper/klipper.cpp b/klipper/klipper.cpp
--- a/klipper/klipper.cpp
+++ b/klipper/klipper.cpp
@@ -39,6 +39,7 @@
 #include <KActionCollection>
 #include <KToggleAction>
 #include <KTextEdit>
+#include <KWindowSystem>
 
 #include "configdialog.h"
 #include "klippersettings.h"
@@ -630,7 +631,7 @@
 //   selected when Klipper asked first.
 // Use XQueryPointer rather than QApplication::mouseButtons()/keyboardModifiers(), because
 //   Klipper needs the very current state.
-    if (!QX11Info::isPlatformX11()) {
+    if (!KWindowSystem::isPlatformX11()) {
         return false;
     }
     xcb_connection_t *c = QX11Info::connection();
@@ -857,7 +858,7 @@
 void Klipper::updateTimestamp()
 {
 #if HAVE_X11
-    if (QX11Info::isPlatformX11()) {
+    if (KWindowSystem::isPlatformX11()) {
         QX11Info::setAppTime(QX11Info::getTimestamp());
     }
 #endif
diff --git a/krunner/view.cpp b/krunner/view.cpp
--- a/krunner/view.cpp
+++ b/krunner/view.cpp
@@ -142,7 +142,7 @@
 
 void View::initWayland()
 {
-    if (!QGuiApplication::platformName().startsWith(QLatin1String("wayland"))) {
+    if (!KWindowSystem::isPlatformWayland()) {
         return;
     }
     using namespace KWayland::Client;
diff --git a/ksplash/ksplashqml/splashapp.cpp b/ksplash/ksplashqml/splashapp.cpp
--- a/ksplash/ksplashqml/splashapp.cpp
+++ b/ksplash/ksplashqml/splashapp.cpp
@@ -72,7 +72,7 @@
 
     setStage(QStringLiteral("initial"));
 
-    if (QGuiApplication::platformName().startsWith(QLatin1String("wayland"), Qt::CaseInsensitive)) {
+    if (KWindowSystem::isPlatformWayland()) {
         setStage(QStringLiteral("wm"));
     }
 
diff --git a/libtaskmanager/launchertasksmodel.cpp b/libtaskmanager/launchertasksmodel.cpp
--- a/libtaskmanager/launchertasksmodel.cpp
+++ b/libtaskmanager/launchertasksmodel.cpp
@@ -25,6 +25,7 @@
 #include <KService>
 #include <KStartupInfo>
 #include <KSycoca>
+#include <KWindowSystem>
 
 #include <config-X11.h>
 
@@ -288,7 +289,7 @@
     quint32 timeStamp = 0;
 
 #if HAVE_X11
-        if (QX11Info::isPlatformX11()) {
+        if (KWindowSystem::isPlatformX11()) {
             timeStamp = QX11Info::appUserTime();
         }
 #endif
diff --git a/libtaskmanager/tasksmodel.cpp b/libtaskmanager/tasksmodel.cpp
--- a/libtaskmanager/tasksmodel.cpp
+++ b/libtaskmanager/tasksmodel.cpp
@@ -162,12 +162,12 @@
     //     -> flattenGroupsProxyModel (optionally, if groupInline == true) flattens groups out.
     //      -> TasksModel collapses (top-level) items into task lifecycle abstraction; sorts.
 
-    if (!windowTasksModel && QGuiApplication::platformName().startsWith(QLatin1String("wayland"))) {
+    if (!windowTasksModel && KWindowSystem::isPlatformWayland()) {
         windowTasksModel = new WaylandTasksModel();
     }
 
 #if HAVE_X11
-    if (!windowTasksModel && QX11Info::isPlatformX11()) {
+    if (!windowTasksModel && KWindowSystem::isPlatformX11()) {
         windowTasksModel = new XWindowTasksModel();
     }
 #endif
diff --git a/libtaskmanager/waylandtasksmodel.cpp b/libtaskmanager/waylandtasksmodel.cpp
--- a/libtaskmanager/waylandtasksmodel.cpp
+++ b/libtaskmanager/waylandtasksmodel.cpp
@@ -28,6 +28,7 @@
 #include <KWayland/Client/plasmawindowmanagement.h>
 #include <KWayland/Client/registry.h>
 #include <KWayland/Client/surface.h>
+#include <KWindowSystem>
 
 #include <QGuiApplication>
 #include <QQuickItem>
@@ -63,7 +64,7 @@
 
 void WaylandTasksModel::Private::initWayland()
 {
-    if (!QGuiApplication::platformName().startsWith(QLatin1String("wayland"), Qt::CaseInsensitive)) {
+    if (!KWindowSystem::isPlatformWayland()) {
         return;
     }
 
diff --git a/shell/panelshadows.cpp b/shell/panelshadows.cpp
--- a/shell/panelshadows.cpp
+++ b/shell/panelshadows.cpp
@@ -23,6 +23,7 @@
 
 #include <config-plasma.h>
 
+#include <KWindowSystem>
 #if HAVE_X11
 #include <QX11Info>
 #include <X11/Xatom.h>
@@ -47,7 +48,7 @@
 #if HAVE_X11
         ,_connection( 0x0 ),
         _gc( 0x0 )
-        , m_isX11(QX11Info::isPlatformX11())
+        , m_isX11(KWindowSystem::isPlatformX11())
 #endif
     {
         setupWaylandIntegration();
@@ -680,7 +681,7 @@
 
 void PanelShadows::Private::setupWaylandIntegration()
 {
-    if (!QGuiApplication::platformName().startsWith(QLatin1String("wayland"), Qt::CaseInsensitive)) {
+    if (!KWindowSystem::isPlatformWayland()) {
         return;
     }
     using namespace KWayland::Client;
diff --git a/shell/panelview.cpp b/shell/panelview.cpp
--- a/shell/panelview.cpp
+++ b/shell/panelview.cpp
@@ -567,7 +567,7 @@
 void PanelView::setAutoHideEnabled(bool enabled)
 {
 #if HAVE_X11
-    if (QX11Info::isPlatformX11()) {
+    if (KWindowSystem::isPlatformX11()) {
         xcb_connection_t *c = QX11Info::connection();
 
         const QByteArray effectName = QByteArrayLiteral("_KDE_NET_WM_SCREEN_EDGE_SHOW");
diff --git a/shell/shellcorona.cpp b/shell/shellcorona.cpp
--- a/shell/shellcorona.cpp
+++ b/shell/shellcorona.cpp
@@ -217,8 +217,7 @@
         watched->inherits("PlasmaQuick::Dialog")) {
         QPlatformSurfaceEvent *se = static_cast<QPlatformSurfaceEvent *>(event);
         if (se->surfaceEventType() == QPlatformSurfaceEvent::SurfaceCreated) {
-            if (QGuiApplication::platformName().startsWith(
-                QLatin1String("wayland"), Qt::CaseInsensitive)) {
+            if (KWindowSystem::isPlatformWayland()) {
                 WaylandDialogFilter::install(qobject_cast<QWindow *>(watched), this);
             }
         }
@@ -1581,7 +1580,7 @@
 
 void ShellCorona::setupWaylandIntegration()
 {
-    if (!QGuiApplication::platformName().startsWith(QLatin1String("wayland"), Qt::CaseInsensitive)) {
+    if (!KWindowSystem::isPlatformWayland()) {
         return;
     }
     using namespace KWayland::Client;
diff --git a/xembed-sni-proxy/main.cpp b/xembed-sni-proxy/main.cpp
--- a/xembed-sni-proxy/main.cpp
+++ b/xembed-sni-proxy/main.cpp
@@ -29,6 +29,8 @@
 
 #include <QtDBus/QtDBus>
 
+#include <KWindowSystem>
+
 namespace Xcb {
     Xcb::Atoms* atoms;
 }
@@ -41,7 +43,7 @@
 
     QGuiApplication app(argc, argv);
 
-    if (app.platformName() != QLatin1String("xcb")) {
+    if (!KWindowSystem::isPlatformX11()) {
         qFatal("xembed-sni-proxy is only useful XCB. Aborting");
     }