diff --git a/platform/core-api/src/com/intellij/openapi/vfs/NonPhysicalFileSystem.java b/platform/core-api/src/com/intellij/openapi/vfs/NonPhysicalFileSystem.java
new file mode 100644
index 000000000000..94fdcd1ec7ee
--- /dev/null
+++ b/platform/core-api/src/com/intellij/openapi/vfs/NonPhysicalFileSystem.java
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2000-2011 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.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.openapi.vfs;
+
+/**
+ * Marker interface for filesystem implementations files in which are considered non-physical.
+ *
+ * @author yole
+ */
+public interface NonPhysicalFileSystem {
+}
diff --git a/platform/lang-impl/src/com/intellij/psi/SingleRootFileViewProvider.java b/platform/lang-impl/src/com/intellij/psi/SingleRootFileViewProvider.java
index 91bb7d36cb96..982114f2c0e1 100644
--- a/platform/lang-impl/src/com/intellij/psi/SingleRootFileViewProvider.java
+++ b/platform/lang-impl/src/com/intellij/psi/SingleRootFileViewProvider.java
@@ -30,8 +30,8 @@ import com.intellij.openapi.progress.ProcessCanceledException;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.util.Key;
 import com.intellij.openapi.util.UserDataHolderBase;
+import com.intellij.openapi.vfs.NonPhysicalFileSystem;
 import com.intellij.openapi.vfs.VirtualFile;
-import com.intellij.openapi.vfs.ex.dummy.DummyFileSystem;
 import com.intellij.openapi.vfs.newvfs.persistent.PersistentFSConstants;
 import com.intellij.psi.impl.PsiFileEx;
 import com.intellij.psi.impl.PsiManagerEx;
@@ -81,7 +81,7 @@ public class SingleRootFileViewProvider extends UserDataHolderBase implements Fi
     setContent(new VirtualFileContent());
     myPhysical = isEventSystemEnabled() &&
                  !(virtualFile instanceof LightVirtualFile) &&
-                 !(virtualFile.getFileSystem() instanceof DummyFileSystem);
+                 !(virtualFile.getFileSystem() instanceof NonPhysicalFileSystem);
     myExclusionManager = ProjectFileExclusionManager.SERVICE.getInstance(manager.getProject());
   }
 
diff --git a/platform/platform-impl/src/com/intellij/openapi/vfs/ex/dummy/DummyFileSystem.java b/platform/platform-impl/src/com/intellij/openapi/vfs/ex/dummy/DummyFileSystem.java
index 19b55e639413..34496269392c 100644
--- a/platform/platform-impl/src/com/intellij/openapi/vfs/ex/dummy/DummyFileSystem.java
+++ b/platform/platform-impl/src/com/intellij/openapi/vfs/ex/dummy/DummyFileSystem.java
@@ -15,10 +15,7 @@
  */
 package com.intellij.openapi.vfs.ex.dummy;
 
-import com.intellij.openapi.vfs.DeprecatedVirtualFileSystem;
-import com.intellij.openapi.vfs.VfsBundle;
-import com.intellij.openapi.vfs.VirtualFile;
-import com.intellij.openapi.vfs.VirtualFileManager;
+import com.intellij.openapi.vfs.*;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -28,7 +25,7 @@ import java.io.IOException;
 /**
  *
  */
-public class DummyFileSystem extends DeprecatedVirtualFileSystem {
+public class DummyFileSystem extends DeprecatedVirtualFileSystem implements NonPhysicalFileSystem {
   @NonNls public static final String PROTOCOL = "dummy";
   private VirtualFileDirectoryImpl myRoot;