diff --git a/effects/wobblywindows/wobblywindows.h b/effects/wobblywindows/wobblywindows.h
--- a/effects/wobblywindows/wobblywindows.h
+++ b/effects/wobblywindows/wobblywindows.h
@@ -133,6 +133,7 @@
     void slotWindowStepUserMovedResized(KWin::EffectWindow *w, const QRect &geometry);
     void slotWindowFinishUserMovedResized(KWin::EffectWindow *w);
     void slotWindowMaximizeStateChanged(KWin::EffectWindow *w, bool horizontal, bool vertical);
+    void slotWindowDeleted(KWin::EffectWindow *w);
 
 private:
 
diff --git a/effects/wobblywindows/wobblywindows.cpp b/effects/wobblywindows/wobblywindows.cpp
--- a/effects/wobblywindows/wobblywindows.cpp
+++ b/effects/wobblywindows/wobblywindows.cpp
@@ -156,6 +156,7 @@
     connect(effects, SIGNAL(windowMaximizedStateChanged(KWin::EffectWindow*,bool,bool)), this, SLOT(slotWindowMaximizeStateChanged(KWin::EffectWindow*,bool,bool)));
 
     connect(effects, &EffectsHandler::windowDataChanged, this, &WobblyWindowsEffect::cancelWindowGrab);
+    connect(effects, &EffectsHandler::windowDeleted, this, &WobblyWindowsEffect::slotWindowDeleted);
 }
 
 WobblyWindowsEffect::~WobblyWindowsEffect()
@@ -1230,6 +1231,15 @@
     }
 }
 
+void WobblyWindowsEffect::slotWindowDeleted(KWin::EffectWindow *w)
+{
+    auto it = windows.find(w);
+    if (it != windows.end()) {
+        freeWobblyInfo(it.value());
+        windows.erase(it);
+    }
+}
+
 bool WobblyWindowsEffect::isActive() const
 {
     return !windows.isEmpty();