diff --git a/platform/util/src/com/intellij/util/containers/TreeTraverser.java b/platform/util/src/com/intellij/util/containers/TreeTraverser.java
index 348b762ee697..337f08863d00 100644
--- a/platform/util/src/com/intellij/util/containers/TreeTraverser.java
+++ b/platform/util/src/com/intellij/util/containers/TreeTraverser.java
@@ -340,6 +340,7 @@ public abstract class TreeTraverser<T> {
     public T next() {
       T result = queue.remove();
       for (T t : children(result)) {
+        if (paths.containsKey(t)) continue;
         queue.add(t);
         paths.put(t, result);
       }