diff --git a/libkwineffects/kwineffects.cpp b/libkwineffects/kwineffects.cpp
--- a/libkwineffects/kwineffects.cpp
+++ b/libkwineffects/kwineffects.cpp
@@ -749,6 +749,7 @@
 {
     // All effects should already be unloaded by Impl dtor
     assert(loaded_effects.count() == 0);
+    KWin::effects = nullptr;
 }
 
 CompositingType EffectsHandler::compositingType() const