diff --git a/effects/coverswitch.cpp b/effects/coverswitch.cpp
index b7369a1990..9bba048590 100644
--- a/effects/coverswitch.cpp
+++ b/effects/coverswitch.cpp
@@ -201,8 +201,10 @@ void CoverSwitchEffect::paintScreen( int mask, QRegion region, ScreenPaintData&
             rightIndex = 0;
 
         EffectWindow* frontWindow = tempList[ index ];
-        leftWindows.clear();
-        rightWindows.clear();
+        if( !leftWindows.isEmpty() )
+            leftWindows.clear();
+        if( !rightWindows.isEmpty() )
+            rightWindows.clear();
 
         bool evenWindows = ( tempList.count() % 2 == 0 ) ? true : false;
         int leftWindowCount = 0;