diff --git a/src/ce_staticexplorer.pas b/src/ce_staticexplorer.pas
index 6d36e57d..cb87c909 100644
--- a/src/ce_staticexplorer.pas
+++ b/src/ce_staticexplorer.pas
@@ -491,6 +491,7 @@ begin
 
   clearTree;
   updateVisibleCat;
+  if fDoc = nil then exit;
 
   if not FileExists(fJsonFname) then exit;