diff --git a/bridge.h b/bridge.h
index 6312ea73ba..200ba68ebd 100644
--- a/bridge.h
+++ b/bridge.h
@@ -28,7 +28,7 @@ namespace KWin
 
 class Client;
 
-class Bridge : public KDecorationBridgeUnstable
+class Bridge : public KDecorationBridge
 {
 public:
     explicit Bridge(Client* cl);
diff --git a/libkdecorations/kdecoration.cpp b/libkdecorations/kdecoration.cpp
index 2a15e6acdd..be92c59117 100644
--- a/libkdecorations/kdecoration.cpp
+++ b/libkdecorations/kdecoration.cpp
@@ -408,10 +408,7 @@ KDecoration::Position KDecoration::mousePosition(const QPoint& p) const
 
 QRect KDecoration::transparentRect() const
 {
-    if (KDecorationBridgeUnstable *bridge2 = dynamic_cast<KDecorationBridgeUnstable*>(bridge_))
-        return bridge2->transparentRect();
-    else
-        return QRect();
+    return bridge_->transparentRect();
 }
 
 void KDecoration::setAlphaEnabled(bool enabled)
@@ -431,7 +428,6 @@ bool KDecoration::isAlphaEnabled() const
 KDecorationUnstable::KDecorationUnstable(KDecorationBridge* bridge, KDecorationFactory* factory)
     : KDecoration(bridge, factory)
 {
-    Q_ASSERT(dynamic_cast< KDecorationBridgeUnstable* >(bridge));
 }
 
 KDecorationUnstable::~KDecorationUnstable()
@@ -440,7 +436,7 @@ KDecorationUnstable::~KDecorationUnstable()
 
 bool KDecorationUnstable::compositingActive() const
 {
-    return static_cast< KDecorationBridgeUnstable* >(bridge_)->compositingActive();
+    return bridge_->compositingActive();
 }
 
 void KDecorationUnstable::padding(int &left, int &right, int &top, int &bottom) const
@@ -452,69 +448,69 @@ void KDecorationUnstable::padding(int &left, int &right, int &top, int &bottom)
 
 int KDecorationUnstable::tabCount() const
 {
-    return static_cast< KDecorationBridgeUnstable* >(bridge_)->tabCount();
+    return bridge_->tabCount();
 }
 
 long KDecorationUnstable::tabId(int idx) const
 {
-    return static_cast< KDecorationBridgeUnstable* >(bridge_)->tabId(idx);
+    return bridge_->tabId(idx);
 }
 
 QString KDecorationUnstable::caption(int idx) const
 {
-    return static_cast< KDecorationBridgeUnstable* >(bridge_)->caption(idx);
+    return bridge_->caption(idx);
 }
 
 QIcon KDecorationUnstable::icon(int idx) const
 {
-    return static_cast< KDecorationBridgeUnstable* >(bridge_)->icon(idx);
+    return bridge_->icon(idx);
 }
 
 long KDecorationUnstable::currentTabId() const
 {
-    return static_cast< KDecorationBridgeUnstable* >(bridge_)->currentTabId();
+    return bridge_->currentTabId();
 }
 
 void KDecorationUnstable::setCurrentTab(long id)
 {
-    static_cast< KDecorationBridgeUnstable* >(bridge_)->setCurrentTab(id);
+    bridge_->setCurrentTab(id);
 }
 
 void KDecorationUnstable::tab_A_before_B(long A, long B)
 {
-    static_cast< KDecorationBridgeUnstable* >(bridge_)->tab_A_before_B(A, B);
+    bridge_->tab_A_before_B(A, B);
 }
 
 void KDecorationUnstable::tab_A_behind_B(long A, long B)
 {
-    static_cast< KDecorationBridgeUnstable* >(bridge_)->tab_A_behind_B(A, B);
+    bridge_->tab_A_behind_B(A, B);
 }
 
 void KDecorationUnstable::untab(long id, const QRect& newGeom)
 {
-    static_cast< KDecorationBridgeUnstable* >(bridge_)->untab(id, newGeom);
+    bridge_->untab(id, newGeom);
 }
 
 void KDecorationUnstable::closeTab(long id)
 {
-    static_cast< KDecorationBridgeUnstable* >(bridge_)->closeTab(id);
+    bridge_->closeTab(id);
 }
 
 void KDecorationUnstable::closeTabGroup()
 {
-    static_cast< KDecorationBridgeUnstable* >(bridge_)->closeTabGroup();
+    bridge_->closeTabGroup();
 }
 
 void KDecorationUnstable::showWindowMenu(const QPoint &pos, long id)
 {
-    static_cast< KDecorationBridgeUnstable* >(bridge_)->showWindowMenu(pos, id);
+    bridge_->showWindowMenu(pos, id);
 }
 
 //END tabbing
 
 KDecoration::WindowOperation KDecorationUnstable::buttonToWindowOperation(Qt::MouseButtons button)
 {
-    return static_cast< KDecorationBridgeUnstable* >(bridge_)->buttonToWindowOperation(button);
+    return bridge_->buttonToWindowOperation(button);
 }
 
 QRegion KDecoration::region(KDecorationDefines::Region)
diff --git a/libkdecorations/kdecorationbridge.h b/libkdecorations/kdecorationbridge.h
index 4f7aadc290..a8dedb1e6e 100644
--- a/libkdecorations/kdecorationbridge.h
+++ b/libkdecorations/kdecorationbridge.h
@@ -84,25 +84,17 @@ public:
     virtual QWidget* initialParentWidget() const = 0;
     virtual Qt::WindowFlags initialWFlags() const = 0;
     virtual void grabXServer(bool grab) = 0;
-};
 
-class KDecorationBridgeUnstable
-    : public KDecorationBridge
-{
-public:
     virtual bool compositingActive() const = 0;
     virtual QRect transparentRect() const = 0;
 
     // Window tabbing
-    using KDecorationBridge::caption;
     virtual QString caption(int idx) const = 0;
     virtual void closeTab(long id) = 0;
     virtual void closeTabGroup() = 0;
     virtual long currentTabId() const = 0;
-    using KDecorationBridge::icon;
     virtual QIcon icon(int idx) const = 0;
     virtual void setCurrentTab(long id) = 0;
-    using KDecorationBridge::showWindowMenu;
     virtual void showWindowMenu(const QPoint& pos, long id) = 0;
     virtual void tab_A_before_B(long A, long B) = 0;
     virtual void tab_A_behind_B(long A, long B) = 0;