diff --git a/kwin/src/breezydesktopeffect.h b/kwin/src/breezydesktopeffect.h
index 9be5552..cae4be4 100644
--- a/kwin/src/breezydesktopeffect.h
+++ b/kwin/src/breezydesktopeffect.h
@@ -17,6 +17,8 @@ class QTimer;
 
 namespace KWin
 {
+    class Output;
+
     class BreezyDesktopEffect : public QuickSceneEffect
     {
         Q_OBJECT