diff --git a/platform/platform-api/src/com/intellij/openapi/vfs/newvfs/RefreshSession.java b/platform/platform-api/src/com/intellij/openapi/vfs/newvfs/RefreshSession.java
index b0b35be25f3f..dcfd68e3955b 100644
--- a/platform/platform-api/src/com/intellij/openapi/vfs/newvfs/RefreshSession.java
+++ b/platform/platform-api/src/com/intellij/openapi/vfs/newvfs/RefreshSession.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2009 JetBrains s.r.o.
+ * Copyright 2000-2012 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -13,10 +13,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
-/*
- * @author max
- */
 package com.intellij.openapi.vfs.newvfs;
 
 import com.intellij.openapi.vfs.VirtualFile;
@@ -25,11 +21,15 @@ import org.jetbrains.annotations.NotNull;
 import java.util.Arrays;
 import java.util.Collection;
 
+/**
+ * @author max
+ */
 public abstract class RefreshSession {
   public abstract boolean isAsynchronous();
 
   public abstract void addFile(@NotNull VirtualFile file);
-  public abstract void addAllFiles(Collection<VirtualFile> files);
+
+  public abstract void addAllFiles(@NotNull Collection<VirtualFile> files);
 
   public void addAllFiles(@NotNull VirtualFile[] files) {
     addAllFiles(Arrays.asList(files));
diff --git a/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/RefreshSessionImpl.java b/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/RefreshSessionImpl.java
index 2a2200896bfd..5100401459be 100644
--- a/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/RefreshSessionImpl.java
+++ b/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/RefreshSessionImpl.java
@@ -71,12 +71,19 @@ public class RefreshSessionImpl extends RefreshSession {
   }
 
   @Override
-  public void addAllFiles(final Collection<VirtualFile> files) {
-    myWorkQueue.addAll(files);
+  public void addAllFiles(@NotNull Collection<VirtualFile> files) {
+    for (VirtualFile file : files) {
+      if (file == null) {
+        LOG.error("null passed among " + files);
+      }
+      else {
+        myWorkQueue.add(file);
+      }
+    }
   }
 
   @Override
-  public void addFile(@NotNull final VirtualFile file) {
+  public void addFile(@NotNull VirtualFile file) {
     myWorkQueue.add(file);
   }