diff --git a/src/plugins/platforms/eglfs/api/qeglfswindow.cpp b/src/plugins/platforms/eglfs/api/qeglfswindow.cpp
index 1a31f97d7b8..6210ef16a8e 100644
--- a/src/plugins/platforms/eglfs/api/qeglfswindow.cpp
+++ b/src/plugins/platforms/eglfs/api/qeglfswindow.cpp
@@ -108,8 +108,12 @@ void QEglFSWindow::create()
 #endif
 }
 
-void QEglFSWindow::setBackingStore(QOpenGLCompositorBackingStore *backingStore)
+void QEglFSWindow::setBackingStore(QPlatformBackingStore *store)
 {
+    Q_ASSERT(store);
+    Q_ASSERT_X(dynamic_cast<QOpenGLCompositorBackingStore *>(store), __FUNCTION__,
+               "Argument is not a QOpenGLCompositorBackingStore.");
+    auto *backingStore = static_cast<QOpenGLCompositorBackingStore *>(store);
 #ifndef QT_NO_OPENGL
     if (!m_rasterCompositingContext) {
         m_rasterCompositingContext = new QOpenGLContext;
diff --git a/src/plugins/platforms/eglfs/api/qeglfswindow_p.h b/src/plugins/platforms/eglfs/api/qeglfswindow_p.h
index d111042040a..d8e0a4a7359 100644
--- a/src/plugins/platforms/eglfs/api/qeglfswindow_p.h
+++ b/src/plugins/platforms/eglfs/api/qeglfswindow_p.h
@@ -71,7 +71,7 @@ public:
 
 #ifndef QT_NO_OPENGL
     QOpenGLCompositorBackingStore *backingStore() { return m_backingStore; }
-    void setBackingStore(QOpenGLCompositorBackingStore *backingStore);
+    void setBackingStore(QPlatformBackingStore *backingStore) override;
     QWindow *sourceWindow() const override;
     const QPlatformTextureList *textures() const override;
     void endCompositing() override;
diff --git a/src/plugins/platforms/wasm/qwasmwindow.cpp b/src/plugins/platforms/wasm/qwasmwindow.cpp
index c9cc78b826c..68d9d2eb1d5 100644
--- a/src/plugins/platforms/wasm/qwasmwindow.cpp
+++ b/src/plugins/platforms/wasm/qwasmwindow.cpp
@@ -232,6 +232,14 @@ QWasmScreen *QWasmWindow::platformScreen() const
     return static_cast<QWasmScreen *>(window()->screen()->handle());
 }
 
+void QWasmWindow::setBackingStore(QPlatformBackingStore *store)
+{
+    Q_ASSERT(store);
+    Q_ASSERT_X(dynamic_cast<QWasmBackingStore *>(store), __FUNCTION__,
+               "Argument is not a QWasmBackingStore.");
+    m_backingStore = static_cast<QWasmBackingStore *>(store);
+}
+
 void QWasmWindow::paint()
 {
     if (!m_backingStore || !isVisible() || m_context2d.isUndefined())
diff --git a/src/plugins/platforms/wasm/qwasmwindow.h b/src/plugins/platforms/wasm/qwasmwindow.h
index 99b490b473f..422a2ea464c 100644
--- a/src/plugins/platforms/wasm/qwasmwindow.h
+++ b/src/plugins/platforms/wasm/qwasmwindow.h
@@ -85,7 +85,7 @@ public:
     void setMask(const QRegion &region) final;
 
     QWasmScreen *platformScreen() const;
-    void setBackingStore(QWasmBackingStore *store) { m_backingStore = store; }
+    void setBackingStore(QPlatformBackingStore *store) override;
     QWasmBackingStore *backingStore() const { return m_backingStore; }
     QWindow *window() const { return m_window; }