diff --git a/ClassData.h b/ClassData.h
index f9d759d..8b8fe63 100644
--- a/ClassData.h
+++ b/ClassData.h
@@ -7,6 +7,8 @@
 #include <cmath>
 #include <cstring>  ///memset
 #include <iostream> ///cout
+#include <sstream>
+#include <iomanip> // for setw
 #include <bitset>
 #include <vector>
 #include <sys/stat.h>
@@ -212,11 +214,19 @@ inline void Data::CopyBuffer(const char * buffer, const unsigned int size){
 inline bool Data::OpenSaveFile(std::string fileNamePrefix){
 
   outFilePrefix = fileNamePrefix;
-  char saveFileName[100];
-  sprintf(saveFileName, "%s_%03d_%3s_%03u.fsu", outFilePrefix.c_str() , boardSN, DPPTypeStr.c_str(), outFileIndex);
+
+  std::ostringstream oss;
+  oss << outFilePrefix << "_"
+      << std::setfill('0') << std::setw(3) << boardSN << "_"
+      << DPPTypeStr << "_"
+      << std::setfill('0') << std::setw(3) << outFileIndex << ".fsu";
+  std::string saveFileName = oss.str();
+
+  //char saveFileName[100];
+  //sprintf(saveFileName, "%s_%03d_%3s_%03u.fsu", outFilePrefix.c_str() , boardSN, DPPTypeStr.c_str(), outFileIndex);
 
   outFileName = saveFileName;
-  outFile = fopen(saveFileName, "wb"); // overwrite binary
+  outFile = fopen(saveFileName.c_str(), "wb"); // overwrite binary
   
   if (outFile == NULL) {
     printf("Failed to open the file. Probably Read-ONLY.\n");
@@ -242,8 +252,17 @@ inline void Data::SaveData(){
     FinishedOutFilesSize += ftell(outFile);
     CloseSaveFile();
     outFileIndex ++;
-    char saveFileName[100];
-    sprintf(saveFileName, "%s_%03d_%3s_%03u.fsu", outFilePrefix.c_str() , boardSN, DPPTypeStr.c_str(), outFileIndex);
+
+    // char saveFileName[100];
+    // sprintf(saveFileName, "%s_%03d_%3s_%03u.fsu", outFilePrefix.c_str() , boardSN, DPPTypeStr.c_str(), outFileIndex);
+
+    std::ostringstream oss;
+    oss << outFilePrefix << "_"
+        << std::setfill('0') << std::setw(3) << boardSN << "_"
+        << DPPTypeStr << "_"
+        << std::setfill('0') << std::setw(3) << outFileIndex << ".fsu";
+    std::string saveFileName = oss.str();
+
     outFileName = saveFileName;
     outFile = fopen(outFileName.c_str(), "wb"); //overwrite binary
   }
diff --git a/EventBuilder.cpp b/EventBuilder.cpp
index c57efcf..3920c66 100644
--- a/EventBuilder.cpp
+++ b/EventBuilder.cpp
@@ -192,10 +192,18 @@ int main(int argc, char **argv) {
   char * buffer = nullptr;
   unsigned int word[1]; // 4 byte = 32 bit
 
-  int lastDataIndex[nGroup][MaxNChannels]={0}; // keep track of the DataIndex
-  int lastLoopIndex[nGroup][MaxNChannels]={0}; // keep track of the DataIndex
+  int lastDataIndex[nGroup][MAX_MULTI]; // keep track of the DataIndex
+  int lastLoopIndex[nGroup][MAX_MULTI]; // keep track of the DataIndex
+  int aggCount[nGroup];
+
+  for( int i = 0; i < nGroup; i++){
+    aggCount[i] = 0;
+    for( int j = 0; j < MAX_MULTI; j++){
+      lastDataIndex[i][j] = 0;
+      lastLoopIndex[i][j] = 0;
+    }
+  }
 
-  int aggCount[nGroup] = {0};
   do{
 
     /// fill the data class with some agg;