diff --git a/shell_client.cpp b/shell_client.cpp
index 7e81e5305c..9d9ccc06f2 100644
--- a/shell_client.cpp
+++ b/shell_client.cpp
@@ -132,6 +132,11 @@ double ShellClient::opacity() const
     return 1.0;
 }
 
+void ShellClient::setOpacity(double opacity)
+{
+    Q_UNUSED(opacity)
+}
+
 void ShellClient::addDamage(const QRegion &damage)
 {
     setReadyForPainting();
diff --git a/shell_client.h b/shell_client.h
index 9742caf647..1c46b71045 100644
--- a/shell_client.h
+++ b/shell_client.h
@@ -50,6 +50,7 @@ public:
     NET::WindowType windowType(bool direct = false, int supported_types = 0) const override;
     void debug(QDebug &stream) const override;
     double opacity() const override;
+    void setOpacity(double opacity) override;
     QByteArray windowRole() const override;
 
     KWayland::Server::ShellSurfaceInterface *shellSurface() const {
diff --git a/toplevel.h b/toplevel.h
index b524009729..49a0d030a1 100644
--- a/toplevel.h
+++ b/toplevel.h
@@ -268,7 +268,7 @@ public:
     bool readyForPainting() const; // true if the window has been already painted its contents
     xcb_visualid_t visual() const;
     bool shape() const;
-    void setOpacity(double opacity);
+    virtual void setOpacity(double opacity);
     virtual double opacity() const;
     int depth() const;
     bool hasAlpha() const;