diff --git a/src/Window.cpp b/src/Window.cpp
index e7abb6e1..bb0c52e1 100644
--- a/src/Window.cpp
+++ b/src/Window.cpp
@@ -228,7 +228,7 @@ CWindow* CWindow::X11TransientFor() {
 
     auto PPARENT = g_pCompositor->getWindowFromSurface(m_uSurface.xwayland->parent->surface);
 
-    while (PPARENT->m_uSurface.xwayland->parent) {
+    while (g_pCompositor->windowValidMapped(PPARENT) && PPARENT->m_uSurface.xwayland->parent) {
         PPARENT = g_pCompositor->getWindowFromSurface(PPARENT->m_uSurface.xwayland->parent->surface);
     }