diff --git a/effects.cpp b/effects.cpp
--- a/effects.cpp
+++ b/effects.cpp
@@ -1736,7 +1736,8 @@
     managed = toplevel->isClient();
 
     waylandClient = qobject_cast<KWin::XdgShellClient *>(toplevel) != nullptr;
-    x11Client = qobject_cast<KWin::X11Client *>(toplevel) != nullptr;
+    x11Client = qobject_cast<KWin::X11Client *>(toplevel) != nullptr ||
+        qobject_cast<KWin::Unmanaged *>(toplevel) != nullptr;
 }
 
 EffectWindowImpl::~EffectWindowImpl()
@@ -1954,7 +1955,7 @@
     if (isX11Client() && sceneWindow()) {
         return sceneWindow()->bufferShape();
     }
-    return geometry();
+    return toplevel->rect();
 }
 
 QRect EffectWindowImpl::decorationInnerRect() const