diff --git a/client.h b/client.h
index fd40416641..239629391f 100644
--- a/client.h
+++ b/client.h
@@ -90,8 +90,12 @@ class Client
      * The desktop this Client is on. If the Client is on all desktops the property has value -1.
      **/
     Q_PROPERTY(int desktop READ desktop WRITE setDesktop NOTIFY desktopChanged)
-    // TODO: notify signal, proper setter with only one attribute
-    Q_PROPERTY(bool fullScreen READ isFullScreen)
+    /**
+     * Whether this Client is fullScreen. A Client might either be fullScreen due to the _NET_WM property
+     * or through a legacy support hack. The fullScreen state can only be changed if the Client does not
+     * use the legacy hack. To be sure whether the state changed, connect to the notify signal.
+     **/
+    Q_PROPERTY(bool fullScreen READ isFullScreen WRITE setFullScreen NOTIFY fullScreenChanged)
     Q_PROPERTY(bool fullScreenable READ isFullScreenable)
     // TODO: notify signal
     Q_PROPERTY(QRect geometry READ geometry WRITE setGeometry)
@@ -221,7 +225,7 @@ public:
     void setMaximize(bool vertically, bool horizontally);
     QRect iconGeometry() const;
 
-    void setFullScreen(bool set, bool user);
+    void setFullScreen(bool set, bool user = true);
     bool isFullScreen() const;
     bool isFullScreenable(bool fullscreen_hack = false) const;
     bool isActiveFullScreen() const;
@@ -533,6 +537,7 @@ signals:
     void activeChanged();
     void captionChanged();
     void desktopChanged();
+    void fullScreenChanged();
 
 private:
     void exportMappingState(int s);   // ICCCM 4.1.3.1, 4.1.4, NETWM 2.5.1
diff --git a/geometry.cpp b/geometry.cpp
index 0e134e03e8..24e953ecb9 100644
--- a/geometry.cpp
+++ b/geometry.cpp
@@ -2428,6 +2428,9 @@ void Client::setFullScreen(bool set, bool user)
 #endif
 
     emit s_fullScreenSet(set, user);
+    if (was_fs != isFullScreen()) {
+        emit fullScreenChanged();
+    }
 }
 
 
@@ -2502,10 +2505,12 @@ void Client::updateFullScreenHack(const QRect& geom)
         } else
             geom = workspace()->clientArea(FullScreenArea, geom.center(), desktop());
         setGeometry(geom);
+        emit fullScreenChanged();
     } else if (fullscreen_mode == FullScreenHack && type == 0) {
         fullscreen_mode = FullScreenNone;
         updateDecoration(false, false);
         // whoever called this must setup correct geometry
+        emit fullScreenChanged();
     }
     StackingUpdatesBlocker blocker(workspace());
     workspace()->updateClientLayer(this);   // active fullscreens get different layer