diff --git a/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/tree/nodes/XDebuggerTreeNode.java b/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/tree/nodes/XDebuggerTreeNode.java
index e01d0ad7ce79..c505a63a9d0d 100644
--- a/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/tree/nodes/XDebuggerTreeNode.java
+++ b/platform/xdebugger-impl/src/com/intellij/xdebugger/impl/ui/tree/nodes/XDebuggerTreeNode.java
@@ -64,7 +64,7 @@ public abstract class XDebuggerTreeNode implements TreeNode, TreeSpeedSearch.Pat
   }
 
   @Override
-  public int getIndex(final TreeNode node) {
+  public int getIndex(@NotNull TreeNode node) {
     if (isLeaf()) return -1;
     return getChildren().indexOf(node);
   }