diff --git a/Rdmp.Dicom/Extraction/FoDicomBased/FoDicomAnonymiser.cs b/Rdmp.Dicom/Extraction/FoDicomBased/FoDicomAnonymiser.cs
index 15c204f..836ae70 100644
--- a/Rdmp.Dicom/Extraction/FoDicomBased/FoDicomAnonymiser.cs
+++ b/Rdmp.Dicom/Extraction/FoDicomBased/FoDicomAnonymiser.cs
@@ -330,7 +330,7 @@ public void ProcessFile(DicomFile dicomFile, IDataLoadEventListener listener, st
             //    "0040,0555",
             //    "00F1,0010"
             //};
-            if (_tagsToKeep.Any())
+            if (_tagsToKeep is not null && _tagsToKeep.Any())
             {
                 foreach (var tag in _tagsToKeep)
                 {