diff --git a/libtaskmanager/xwindowtasksmodel.cpp b/libtaskmanager/xwindowtasksmodel.cpp
--- a/libtaskmanager/xwindowtasksmodel.cpp
+++ b/libtaskmanager/xwindowtasksmodel.cpp
@@ -307,24 +307,19 @@
         const KWindowInfo info(window, NET::WMState | NET::XAWMState, NET::WM2TransientFor);
 
         if (info.hasState(NET::DemandsAttention)) {
-            WId oldLeader = info.transientFor();
             QMutableHashIterator<WId, WId> i(transientsDemandingAttention);
 
-            while (i.hasNext()) {
-                i.next();
+            if (i.findNext(window)) {
+                const WId leader = info.transientFor();
+                const WId oldLeader = i.key();
 
-                if (i.value() == window) {
-                    oldLeader = i.key();
+                if (leader != oldLeader) {
                     i.remove();
+                    transientsDemandingAttention.insertMulti(leader, window);
+                    dataChanged(oldLeader, QVector<int>{IsDemandingAttention});
+                    dataChanged(leader, QVector<int>{IsDemandingAttention});
                 }
             }
-
-            if (oldLeader != 0) {
-                const WId leader = info.transientFor();
-                transientsDemandingAttention.insertMulti(leader, window);
-                dataChanged(oldLeader, QVector<int>{IsDemandingAttention});
-                dataChanged(leader, QVector<int>{IsDemandingAttention});
-            }
         }
     }
 }