diff --git a/ide/main.pp b/ide/main.pp
index 7cc95717e6..a1a7b3e46f 100644
--- a/ide/main.pp
+++ b/ide/main.pp
@@ -6063,6 +6063,7 @@ begin
     Result.EndUpdate;
 
   Result.MainProject:=true;
+  Result.OnFileBackup:=@MainBuildBoss.BackupFileForWrite;
   Result.OnLoadProjectInfo:=@OnLoadProjectInfoFromXMLConfig;
   Result.OnSaveProjectInfo:=@OnSaveProjectInfoToXMLConfig;
   Result.OnSaveUnitSessionInfo:=@OnSaveProjectUnitSessionInfo;