diff --git a/Code/Mantid/Framework/DataHandling/src/LoadEventPreNexus.cpp b/Code/Mantid/Framework/DataHandling/src/LoadEventPreNexus.cpp
index c35faa61ac584d58977024502b40fcf32507ce29..bfb4531631743c2344f9b3107513d5b7ed85da8f 100644
--- a/Code/Mantid/Framework/DataHandling/src/LoadEventPreNexus.cpp
+++ b/Code/Mantid/Framework/DataHandling/src/LoadEventPreNexus.cpp
@@ -236,7 +236,7 @@ static string generateMappingfileName(EventWorkspace_sptr &wksp)
   if (!base.exists())
   {
     instrument = Kernel::ConfigService::Instance().getInstrument(instrument).shortName();
-    base = ("/SNS/" + instrument + "/");
+    base = Poco::File("/SNS/" + instrument + "/");
     if (!base.exists())
       return "";
   }