diff --git a/platform/core-impl/src/com/intellij/openapi/vfs/impl/VirtualFileManagerImpl.java b/platform/core-impl/src/com/intellij/openapi/vfs/impl/VirtualFileManagerImpl.java
index 17d2fed49714..23e71b6083c5 100644
--- a/platform/core-impl/src/com/intellij/openapi/vfs/impl/VirtualFileManagerImpl.java
+++ b/platform/core-impl/src/com/intellij/openapi/vfs/impl/VirtualFileManagerImpl.java
@@ -29,6 +29,7 @@ import kotlin.Unit;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;
 
 import java.nio.file.FileSystems;
 import java.nio.file.Path;
@@ -191,8 +192,8 @@ public class VirtualFileManagerImpl extends VirtualFileManager implements Dispos
   }
 
   @ApiStatus.Internal
-  public void addAsyncFileListenersTo(@NotNull List<? super AsyncFileListener> listeners) {
-    listeners.addAll(asyncFileListeners);
+  public @NotNull @Unmodifiable List<AsyncFileListener> withAsyncFileListeners(@NotNull @Unmodifiable List<AsyncFileListener> listeners) {
+    return ContainerUtil.concat(listeners, asyncFileListeners);
   }
 
   @Override
diff --git a/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/AsyncEventSupport.java b/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/AsyncEventSupport.java
index 1e43b5923857..fb3bc8471405 100644
--- a/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/AsyncEventSupport.java
+++ b/platform/platform-impl/src/com/intellij/openapi/vfs/newvfs/AsyncEventSupport.java
@@ -80,8 +80,8 @@ public final class AsyncEventSupport {
     }
 
     List<AsyncFileListener.ChangeApplier> appliers = new ArrayList<>();
-    List<AsyncFileListener> allListeners = new ArrayList<>(EP_NAME.getExtensionList());
-    ((VirtualFileManagerImpl)VirtualFileManager.getInstance()).addAsyncFileListenersTo(allListeners);
+    List<AsyncFileListener> allListeners =
+      ((VirtualFileManagerImpl)VirtualFileManager.getInstance()).withAsyncFileListeners(EP_NAME.getExtensionList());
     for (AsyncFileListener listener : allListeners) {
       ProgressManager.checkCanceled();
       long startNs = System.nanoTime();