diff --git a/kcm/kcm.h b/kcm/kcm.h
--- a/kcm/kcm.h
+++ b/kcm/kcm.h
@@ -37,12 +37,10 @@
 class ConfigPropertyMap;
 }
 
+
 class ScreenLockerKcm : public KCModule
 {
     Q_OBJECT
-    Q_PROPERTY(KDeclarative::ConfigPropertyMap *wallpaperConfiguration READ wallpaperConfiguration NOTIFY wallpaperConfigurationChanged)
-    Q_PROPERTY(QString currentWallpaper READ currentWallpaper NOTIFY currentWallpaperChanged)
-
 public:
     enum Roles {
         PluginNameRole = Qt::UserRole +1,
@@ -76,3 +74,32 @@
     ScreenLockerKcmForm *m_ui;
     ScreenLocker::WallpaperIntegration *m_wallpaperIntegration = nullptr;
 };
+
+//see https://bugreports.qt.io/browse/QTBUG-57714, don't expose a QWidget as a context property
+class ScreenLockerProxy : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(KDeclarative::ConfigPropertyMap *wallpaperConfiguration READ wallpaperConfiguration NOTIFY wallpaperConfigurationChanged)
+    Q_PROPERTY(QString currentWallpaper READ currentWallpaper NOTIFY currentWallpaperChanged)
+public:
+    ScreenLockerProxy(ScreenLockerKcm *parent) :
+        QObject(parent),
+        q(parent)
+    {
+    }
+
+    KDeclarative::ConfigPropertyMap *wallpaperConfiguration() const {
+        return q->wallpaperConfiguration();
+    }
+
+    QString currentWallpaper() const {
+        return q->currentWallpaper();
+    }
+
+signals:
+    void wallpaperConfigurationChanged();
+    void currentWallpaperChanged();
+
+private:
+    ScreenLockerKcm* q;
+};
diff --git a/kcm/kcm.cpp b/kcm/kcm.cpp
--- a/kcm/kcm.cpp
+++ b/kcm/kcm.cpp
@@ -87,7 +87,12 @@
     m_ui->wallpaperCombo->installEventFilter(this);
 
     m_ui->wallpaperConfigWidget->setClearColor(m_ui->palette().color(QPalette::Active, QPalette::Window));
-    m_ui->wallpaperConfigWidget->rootContext()->setContextProperty("configDialog", this);
+    auto proxy = new ScreenLockerProxy(this);
+    m_ui->wallpaperConfigWidget->rootContext()->setContextProperty("configDialog", proxy);
+
+    connect(this, &ScreenLockerKcm::wallpaperConfigurationChanged, proxy, &ScreenLockerProxy::wallpaperConfigurationChanged);
+    connect(this, &ScreenLockerKcm::currentWallpaperChanged, proxy, &ScreenLockerProxy::currentWallpaperChanged);
+
     m_ui->wallpaperConfigWidget->setSource(QUrl(QStringLiteral("qrc:/kscreenlocker-kcm-resources/config.qml")));
     connect(m_ui->wallpaperConfigWidget->rootObject(), SIGNAL(configurationChanged()), this, SLOT(changed()));