diff --git a/effects/kscreen/kscreen.cpp b/effects/kscreen/kscreen.cpp
--- a/effects/kscreen/kscreen.cpp
+++ b/effects/kscreen/kscreen.cpp
@@ -101,13 +101,25 @@
 {
     switch (m_state) {
     case StateFadingOut:
-        data.multiplyOpacity(1.0 - m_timeLine.currentValue());
+        if (w->hasAlpha()) {
+            data.multiplyOpacity(1.0 - m_timeLine.currentValue());
+        } else {
+            data.multiplyBrightness(1.0 - m_timeLine.currentValue());
+        }
         break;
     case StateFadedOut:
-        data.multiplyOpacity(0.0);
+        if (w->hasAlpha()) {
+            data.multiplyOpacity(0.0);
+        } else {
+            data.multiplyBrightness(0.0);
+        }
         break;
     case StateFadingIn:
-        data.multiplyOpacity(m_timeLine.currentValue());
+        if (w->hasAlpha()) {
+            data.multiplyOpacity(m_timeLine.currentValue());
+        } else {
+            data.multiplyBrightness(m_timeLine.currentValue());
+        }
         break;
     default:
         // no adjustment