diff --git a/IRaCIS.Core.API/Controllers/UploadDownLoadController.cs b/IRaCIS.Core.API/Controllers/UploadDownLoadController.cs
index 794f3025a..37cdc4814 100644
--- a/IRaCIS.Core.API/Controllers/UploadDownLoadController.cs
+++ b/IRaCIS.Core.API/Controllers/UploadDownLoadController.cs
@@ -2071,7 +2071,7 @@ namespace IRaCIS.Core.API.Controllers
                     {
                         abortToken.ThrowIfCancellationRequested();
 
-                        var studyTime = study.StudyTime?.ToString("yyyy-MM-dd HH:mm:ss") ?? "UnknownTime";
+                        var studyTime = study.StudyTime?.ToString("yyyyMMdd_HHmmss") ?? "UnknownTime";
                         var modalitysStr = string.Join('_', study.SeriesList.Select(t => t.Modality).Distinct());
 
                         // ---------- DICOMDIR ----------