diff --git a/client.cpp b/client.cpp
index fa72b52698..9f99937737 100644
--- a/client.cpp
+++ b/client.cpp
@@ -239,6 +239,7 @@ void Client::releaseWindow( bool on_shutdown )
     del->unrefWindow();
     deleteClient( this, Allowed );
     ungrabXServer();
+    checkNonExistentClients();
     }
 
 // like releaseWindow(), but this one is called when the window has been already destroyed
@@ -277,6 +278,7 @@ void Client::destroyClient()
     disownDataPassedToDeleted();
     del->unrefWindow();
     deleteClient( this, Allowed );
+    checkNonExistentClients();
     }
 
 void Client::updateDecoration( bool check_workspace_pos, bool force )
diff --git a/group.cpp b/group.cpp
index 9b6f76aa48..031744d608 100644
--- a/group.cpp
+++ b/group.cpp
@@ -49,6 +49,8 @@ namespace KWin
 #endif
 
 #ifdef ENABLE_TRANSIENCY_CHECK
+static bool transiencyCheckNonExistent = false;
+
 bool performTransiencyCheck()
     {
     bool ret = true;
@@ -74,7 +76,8 @@ bool performTransiencyCheck()
                  it2 != mains.end();
                  ++it2 )
                 {
-                if( !Workspace::self()->clients.contains( *it2 )
+                if( transiencyCheckNonExistent
+                    && !Workspace::self()->clients.contains( *it2 )
                     && !Workspace::self()->desktops.contains( *it2 ))
                     {
                     kDebug() << "TC:" << *it1 << " has non-existent main client " << endl;
@@ -94,7 +97,8 @@ bool performTransiencyCheck()
              it2 != trans.end();
              ++it2 )
             {
-            if( !Workspace::self()->clients.contains( *it2 )
+            if( transiencyCheckNonExistent
+                && !Workspace::self()->clients.contains( *it2 )
                 && !Workspace::self()->desktops.contains( *it2 ))
                 {
                 kDebug() << "TC:" << *it1 << " has non-existent transient " << endl;
@@ -115,13 +119,16 @@ bool performTransiencyCheck()
 static QString transiencyCheckStartBt;
 static const Client* transiencyCheckClient;
 static int transiencyCheck = 0;
-static void startTransiencyCheck( const QString& bt, const Client* c )
+
+static void startTransiencyCheck( const QString& bt, const Client* c, bool ne )
     {
     if( ++transiencyCheck == 1 )
         {
         transiencyCheckStartBt = bt;
         transiencyCheckClient = c;
         }
+    if( ne )
+        transiencyCheckNonExistent = true;
     }
 static void checkTransiency()
     {
@@ -133,21 +140,32 @@ static void checkTransiency()
             kdDebug() << "CLIENT:" << transiencyCheckClient << endl;
             assert( false );
             }
+        transiencyCheckNonExistent = false;
         }
     }
 class TransiencyChecker
     {
     public:
-        TransiencyChecker( const QString& bt, const Client*c ) { startTransiencyCheck( bt, c ); }
+        TransiencyChecker( const QString& bt, const Client*c ) { startTransiencyCheck( bt, c, false ); }
         ~TransiencyChecker() { checkTransiency(); }
     };
 
+void checkNonExistentClients()
+    {
+    startTransiencyCheck( kdBacktrace(), NULL, true );
+    checkTransiency();
+    }
+
 #define TRANSIENCY_CHECK( c ) TransiencyChecker transiency_checker( kdBacktrace(), c )
 
 #else
 
 #define TRANSIENCY_CHECK( c )
 
+void checkNonExistentClients()
+    {
+    }
+
 #endif
 
 //********************************************
diff --git a/utils.h b/utils.h
index 981b4202c1..98e7f285bc 100644
--- a/utils.h
+++ b/utils.h
@@ -325,6 +325,8 @@ int qtToX11State( Qt::MouseButtons buttons, Qt::KeyboardModifiers modifiers );
 Qt::MouseButtons x11ToQtMouseButtons( int state );
 Qt::KeyboardModifiers x11ToQtKeyboardModifiers( int state );
 
+void checkNonExistentClients();
+
 #ifndef KCMRULES
 // Qt dialogs emit no signal when closed :(
 
diff --git a/workspace.cpp b/workspace.cpp
index 2b3701dfc4..afeb3cdfb5 100644
--- a/workspace.cpp
+++ b/workspace.cpp
@@ -561,6 +561,7 @@ void Workspace::addClient( Client* c, allowed_t )
     updateStackingOrder( true ); // propagate new client
     if( c->isUtility() || c->isMenu() || c->isToolbar())
         updateToolWindows( true );
+    checkNonExistentClients();
     if( tab_grab )
         tab_box->reset( true );
     }