diff --git a/src/TTimingSubtractionProcessor.cc b/src/TTimingSubtractionProcessor.cc
index 47f699df1964b9c983d1634256908a7795cc2e59..f5114c64490d26205d697ed2c06ca92da37f21c0 100644
--- a/src/TTimingSubtractionProcessor.cc
+++ b/src/TTimingSubtractionProcessor.cc
@@ -38,7 +38,7 @@ TTimingSubtractionProcessor::TTimingSubtractionProcessor()
 			   &fStartTimingData,"TClonesArray","art::ITiming");
    RegisterOutputCollection("OutputCollection","output collection name",
 			    fOutputColName,TString("plastic_tof"));
-   RegisterProcessorParameter("StartTimingDetID","detID of reference timing source",
+   RegisterProcessorParameter("StartTimingDetID","detID of reference timing source (if -1 use any id)",
                               fStartTimingDetID,1);
    RegisterProcessorParameter("UseMultipleStartTiming",
 			      "enables multihit start timing treatment. If non-zero, output class is art::TTimeDiffernce, else, it is identical to input. In the latter case, both Get/SetTiming() must be available in that class.",
@@ -117,7 +117,7 @@ void TTimingSubtractionProcessor::Process()
       TDataObject *const startData = static_cast<TDataObject*>((*fStartTimingData)->At(i));
       const ITiming *const startDataT = dynamic_cast<ITiming*>(startData);
       if ( startData
-	   && startData->GetID() == fStartTimingDetID
+	   && (fStartTimingDetID < 0 || startData->GetID() == fStartTimingDetID)
 	   && IsValid(startDataT->GetTiming()) ) {
 	 fStartTiming->Add(startData);
       }