diff --git a/components/codetools/finddeclarationtool.pas b/components/codetools/finddeclarationtool.pas
index b555219d3d..6a5ca30437 100644
--- a/components/codetools/finddeclarationtool.pas
+++ b/components/codetools/finddeclarationtool.pas
@@ -5831,6 +5831,7 @@ begin
   //debugln(['TFindDeclarationTool.BuildInterfaceIdentifierCache BEFORE ',MainFilename]);
   BuildTree(true);
   //debugln(['TFindDeclarationTool.BuildInterfaceIdentifierCache AFTER ',MainFilename]);
+  if Tree.Root=nil then exit;
 
   // search interface section
   InterfaceNode:=FindInterfaceNode;