diff --git a/Framework/DataHandling/src/LoadBBY.cpp b/Framework/DataHandling/src/LoadBBY.cpp
index 5c670badbacd110171d22b117186b3d4f9f54c32..e117a87dd617cc5e692cc6004b882e83dfb34e31 100644
--- a/Framework/DataHandling/src/LoadBBY.cpp
+++ b/Framework/DataHandling/src/LoadBBY.cpp
@@ -405,6 +405,7 @@ void LoadBBY::exec() {
       createChildAlgorithm("LoadInstrument");
   loadInstrumentAlg->setProperty("Workspace", eventWS);
   loadInstrumentAlg->setPropertyValue("InstrumentName", "BILBY");
+  loadInstrumentAlg->setProperty("RewriteSpectraMap", false);
   loadInstrumentAlg->executeAsChildAlg();
 
   setProperty("OutputWorkspace", eventWS);
@@ -826,4 +827,4 @@ void BbyDetectorBankFactory::createAndAssign(size_t startIndex,
 }
 
 } // DataHandling
-} // Mantid
\ No newline at end of file
+} // Mantid