diff --git a/layers.cpp b/layers.cpp
index d8c75776db..ff434ecaea 100644
--- a/layers.cpp
+++ b/layers.cpp
@@ -262,19 +262,19 @@ Client* Workspace::topClientOnDesktop(int desktop, int screen, bool unconstraine
     return 0;
 }
 
-Client* Workspace::findDesktop(bool topmost, int desktop) const
+AbstractClient* Workspace::findDesktop(bool topmost, int desktop) const
 {
 // TODO    Q_ASSERT( block_stacking_updates == 0 );
     if (topmost) {
         for (int i = stacking_order.size() - 1; i >= 0; i--) {
-            Client *c = qobject_cast<Client*>(stacking_order.at(i));
+            AbstractClient *c = qobject_cast<AbstractClient*>(stacking_order.at(i));
             if (c && c->isOnDesktop(desktop) && c->isDesktop()
                     && c->isShown(true))
                 return c;
         }
     } else { // bottom-most
         foreach (Toplevel * c, stacking_order) {
-            Client *client = qobject_cast<Client*>(c);
+            AbstractClient *client = qobject_cast<AbstractClient*>(c);
             if (client && c->isOnDesktop(desktop) && c->isDesktop()
                     && client->isShown(true))
                 return client;
diff --git a/workspace.cpp b/workspace.cpp
index e10ee07a50..fc9f80f0c4 100644
--- a/workspace.cpp
+++ b/workspace.cpp
@@ -352,7 +352,7 @@ void Workspace::init()
 
     } // End updates blocker block
 
-    Client* new_active_client = NULL;
+    AbstractClient* new_active_client = nullptr;
     if (!qApp->isSessionRestored()) {
         --block_focus;
         new_active_client = findClient(Predicate::WindowMatch, client_info.activeWindow());
diff --git a/workspace.h b/workspace.h
index 89cccd6f70..3da9efa4b4 100644
--- a/workspace.h
+++ b/workspace.h
@@ -247,7 +247,7 @@ public:
 
     Client* topClientOnDesktop(int desktop, int screen, bool unconstrained = false,
                                bool only_normal = true) const;
-    Client* findDesktop(bool topmost, int desktop) const;
+    AbstractClient* findDesktop(bool topmost, int desktop) const;
     void sendClientToDesktop(AbstractClient* c, int desktop, bool dont_activate);
     void windowToPreviousDesktop(AbstractClient* c);
     void windowToNextDesktop(AbstractClient* c);