diff --git a/effects.cpp b/effects.cpp
index 2f344dd865..10a6a6df41 100644
--- a/effects.cpp
+++ b/effects.cpp
@@ -102,6 +102,7 @@ EffectsHandlerImpl::EffectsHandlerImpl(CompositingType type)
     connect(ws, SIGNAL(unmanagedAdded(KWin::Unmanaged*)), this, SLOT(slotUnmanagedAdded(KWin::Unmanaged*)));
     connect(ws, SIGNAL(clientActivated(KWin::Client*)), this, SLOT(slotClientActivated(KWin::Client*)));
     connect(ws, SIGNAL(deletedRemoved(KWin::Deleted*)), this, SLOT(slotDeletedRemoved(KWin::Deleted*)));
+    connect(ws, SIGNAL(numberDesktopsChanged(int)), SIGNAL(numberDesktopsChanged(int)));
     connect(ws->tabBox(), SIGNAL(tabBoxAdded(int)), SIGNAL(tabBoxAdded(int)));
     connect(ws->tabBox(), SIGNAL(tabBoxUpdated()), SIGNAL(tabBoxUpdated()));
     connect(ws->tabBox(), SIGNAL(tabBoxClosed()), SIGNAL(tabBoxClosed()));
@@ -497,12 +498,6 @@ void EffectsHandlerImpl::propertyNotify(EffectWindow* c, long atom)
     ep.second->propertyNotify(c, atom);
 }
 
-void EffectsHandlerImpl::numberDesktopsChanged(int old)
-{
-    foreach (const EffectPair & ep, loaded_effects)
-    ep.second->numberDesktopsChanged(old);
-}
-
 void EffectsHandlerImpl::registerPropertyType(long atom, bool reg)
 {
     if (reg)
diff --git a/effects.h b/effects.h
index 5d81465e24..7ea1ad071b 100644
--- a/effects.h
+++ b/effects.h
@@ -171,7 +171,6 @@ public:
     void grabbedKeyboardEvent(QKeyEvent* e);
     bool hasKeyboardGrab() const;
     void propertyNotify(EffectWindow* c, long atom);
-    void numberDesktopsChanged(int old);
 
     bool loadEffect(const QString& name);
     void toggleEffect(const QString& name);
diff --git a/effects/desktopgrid/desktopgrid.cpp b/effects/desktopgrid/desktopgrid.cpp
index 4fa4267d5f..a8cf93481a 100644
--- a/effects/desktopgrid/desktopgrid.cpp
+++ b/effects/desktopgrid/desktopgrid.cpp
@@ -76,6 +76,7 @@ DesktopGridEffect::DesktopGridEffect()
     connect(effects, SIGNAL(windowAdded(EffectWindow*)), this, SLOT(slotWindowAdded(EffectWindow*)));
     connect(effects, SIGNAL(windowClosed(EffectWindow*)), this, SLOT(slotWindowClosed(EffectWindow*)));
     connect(effects, SIGNAL(windowDeleted(EffectWindow*)), this, SLOT(slotWindowDeleted(EffectWindow*)));
+    connect(effects, SIGNAL(numberDesktopsChanged(int)), this, SLOT(slotNumberDesktopsChanged(int)));
 
     // Load all other configuration details
     reconfigure(ReconfigureAll);
@@ -1259,7 +1260,7 @@ void DesktopGridEffect::slotRemoveDesktop()
     effects->setNumberOfDesktops(effects->numberOfDesktops() - 1);
 }
 
-void DesktopGridEffect::numberDesktopsChanged(int old)
+void DesktopGridEffect::slotNumberDesktopsChanged(int old)
 {
     if (!activated)
         return;
diff --git a/effects/desktopgrid/desktopgrid.h b/effects/desktopgrid/desktopgrid.h
index 17aadeb21f..ea08abcee4 100644
--- a/effects/desktopgrid/desktopgrid.h
+++ b/effects/desktopgrid/desktopgrid.h
@@ -75,7 +75,6 @@ public:
     virtual void windowInputMouseEvent(Window w, QEvent* e);
     virtual void grabbedKeyboardEvent(QKeyEvent* e);
     virtual bool borderActivated(ElectricBorder border);
-    virtual void numberDesktopsChanged(int old);
 
     enum { LayoutPager, LayoutAutomatic, LayoutCustom }; // Layout modes
 
@@ -89,6 +88,7 @@ private slots:
     void slotWindowAdded(EffectWindow* w);
     void slotWindowClosed(EffectWindow *w);
     void slotWindowDeleted(EffectWindow *w);
+    void slotNumberDesktopsChanged(int old);
 
 private:
     QPointF scalePos(const QPoint& pos, int desktop, int screen = -1) const;
diff --git a/libkwineffects/kwineffects.cpp b/libkwineffects/kwineffects.cpp
index f5db79c95e..8c2352fcde 100644
--- a/libkwineffects/kwineffects.cpp
+++ b/libkwineffects/kwineffects.cpp
@@ -263,10 +263,6 @@ double Effect::animationTime(int defaultTime)
     return qMax(defaultTime * effects->animationTimeFactor(), 1.);
 }
 
-void Effect::numberDesktopsChanged(int)
-{
-}
-
 //****************************************
 // EffectsHandler
 //****************************************
diff --git a/libkwineffects/kwineffects.h b/libkwineffects/kwineffects.h
index 0b59bab221..d17488fc3f 100644
--- a/libkwineffects/kwineffects.h
+++ b/libkwineffects/kwineffects.h
@@ -463,13 +463,6 @@ public:
 
     virtual bool borderActivated(ElectricBorder border);
 
-    /**
-    * called when the number of currently existing desktops is changed.
-    * @param old The previous number of desktops in used.
-    * @see EffectsHandler::numberOfDesktops.
-    */
-    virtual void numberDesktopsChanged(int old);
-
     static int displayWidth();
     static int displayHeight();
     static QPoint cursorPos();
@@ -826,6 +819,13 @@ Q_SIGNALS:
      * @since 4.7
      **/
     void desktopChanged(int oldDesktop, int newDesktop);
+    /**
+    * Signal emitted when the number of currently existing desktops is changed.
+    * @param old The previous number of desktops in used.
+    * @see EffectsHandler::numberOfDesktops.
+    * @since 4.7
+    */
+    void numberDesktopsChanged(int old);
     /**
      * Signal emitted when a new window has been added to the Workspace.
      * @param w The added window
diff --git a/workspace.cpp b/workspace.cpp
index be725d5b84..a42164368f 100644
--- a/workspace.cpp
+++ b/workspace.cpp
@@ -1686,9 +1686,7 @@ void Workspace::setNumberOfDesktops(int n)
 
     // reset the desktop change osd
     desktop_change_osd->numberDesktopsChanged();
-    // inform effects
-    if (effects)
-        static_cast< EffectsHandlerImpl* >(effects)->numberDesktopsChanged(old_number_of_desktops);
+    emit numberDesktopsChanged(old_number_of_desktops);
 }
 
 /**
diff --git a/workspace.h b/workspace.h
index 4e49fd2dd5..5389db087e 100644
--- a/workspace.h
+++ b/workspace.h
@@ -922,6 +922,7 @@ Q_SIGNALS:
 signals:
     void desktopPresenceChanged(KWin::Client*, int);
     void currentDesktopChanged(int);
+    void numberDesktopsChanged(int oldNumberOfDesktops);
     void clientAdded(KWin::Client*);
     void clientRemoved(KWin::Client*);
     void clientActivated(KWin::Client*);