--- v01-00-01/source/BeamCalReco/src/BeamCalBkgPregen.cpp.orig	2019-12-12 00:18:26.000000000 +0900
+++ v01-00-01/source/BeamCalReco/src/BeamCalBkgPregen.cpp	2020-03-18 20:34:42.000000000 +0900
@@ -29,6 +29,10 @@
 #include <map>
 #include <set>
 #include <stdexcept>
+#if 0
+#else
+#include <random>
+#endif
 
 using std::vector;
 using std::string;
@@ -67,7 +71,13 @@
   m_backgroundBX = new TChain("bcTree");
 
   //mix up the files, because the random numbers are ordered to avoid repeating
+#if 0
   std::random_shuffle(bg_files.begin(), bg_files.end());
+#else
+  std::random_device seed_gen;
+  std::mt19937 engine(seed_gen());
+  std::shuffle(bg_files.begin(), bg_files.end(), engine);
+#endif
 
   for (std::vector<std::string>::iterator file = bg_files.begin(); file != bg_files.end(); ++file) {
     streamlog_out(DEBUG1) << *file << std::endl;