diff --git a/platform/lang-impl/src/com/intellij/ide/hierarchy/HierarchyBrowserBaseEx.java b/platform/lang-impl/src/com/intellij/ide/hierarchy/HierarchyBrowserBaseEx.java
index 797b793fd4cc..0557c5e0903c 100644
--- a/platform/lang-impl/src/com/intellij/ide/hierarchy/HierarchyBrowserBaseEx.java
+++ b/platform/lang-impl/src/com/intellij/ide/hierarchy/HierarchyBrowserBaseEx.java
@@ -479,7 +479,7 @@ public abstract class HierarchyBrowserBaseEx extends HierarchyBrowserBase implem
   }
 
   private void disposeBuilders() {
-    final Collection<HierarchyTreeBuilder> builders = myBuilders.values();
+    final Collection<HierarchyTreeBuilder> builders = new ArrayList<HierarchyTreeBuilder>(myBuilders.values());
     for (final HierarchyTreeBuilder builder : builders) {
       Disposer.dispose(builder);
     }