diff --git a/ide/unitdependencies.pas b/ide/unitdependencies.pas
index 342fc6c130..6247bdfa39 100644
--- a/ide/unitdependencies.pas
+++ b/ide/unitdependencies.pas
@@ -284,7 +284,7 @@ var
 begin
   if Stage<>cdPostPaint then exit;
   UnitNode:=TUnitNode(Node.Data);
-  if UnitNode.IsFirstImplementationNode then begin
+  if (UnitNode<>nil) and UnitNode.IsFirstImplementationNode then begin
     NodeRect:=Node.DisplayRect(false);
     NodeRect.Left:=Node.DisplayStateIconLeft;
     with Node.TreeView.Canvas do begin