diff --git a/src/external/MusrRoot/TMusrRunHeader.cpp b/src/external/MusrRoot/TMusrRunHeader.cpp
index 040a29067..2c9728d04 100644
--- a/src/external/MusrRoot/TMusrRunHeader.cpp
+++ b/src/external/MusrRoot/TMusrRunHeader.cpp
@@ -344,7 +344,7 @@ Bool_t TMusrRunHeader::FillFolder(TFolder *folder)
   bool found=false;
 
   if (folder == nullptr) {
-    std::cerr << std::endl << ">> TMusrRunHeader::FillFolder(): **ERROR** folder == 0!!" << std::endl;
+    std::cerr << std::endl << ">> TMusrRunHeader::FillFolder(): **ERROR** folder == nullptr!!" << std::endl;
     return false;
   }
 
@@ -405,9 +405,58 @@ Bool_t TMusrRunHeader::FillFolder(TFolder *folder)
  *
  * \param dir to be filled
  */
-Bool_t TMusrRunHeader::FillDirectory(TDirectoryFile *dir)
+Bool_t TMusrRunHeader::FillDirectory(TDirectory *dir)
 {
-  // NOT YET IMPLEMENTED
+  if (dir == nullptr) {
+    std::cerr << std::endl << ">> TMusrRunHeader::FillDirectory(): **ERROR** dir == nullptr!!" << std::endl;
+    return false;
+  }
+
+  if (!UpdateDirTree(dir))
+    return false;
+
+  // update/generate tree content
+  TString path, name, str;
+  TObjString ostr, *p_ostr;
+  Ssiz_t pos=0;
+  TDirectory *currDir=nullptr;
+  TObjArray *oarray=nullptr;
+  Bool_t found;
+  for (UInt_t i=0; i<fPathNameOrder.size(); i++) {
+    path=fPathNameOrder[i];
+    pos = path.Last('/');
+    if (pos == -1) {
+      std::cerr << std::endl << ">> TMusrRunHeader::FillDirectory(): **ERROR** somethig is wrong with the path=" << path << " !!" << std::endl;
+      return false;
+    }
+    path.Remove(pos); // remove the value from the path
+    dir->cd(path);
+    currDir = dir->CurrentDirectory();
+    if (currDir->GetList()->Last() == nullptr) { // no oarray present, hence create it
+      oarray = new TObjArray();
+    } else {
+      oarray = dynamic_cast<TObjArray*>(currDir->GetList()->First());
+    }
+
+    // check if <value> is already found in oarray
+    ostr = GetHeaderString(i); // encode the string for the MusrRoot file
+    name = ostr.GetString(); // convert to TString
+    str = GetFirst(name, ':'); // get the first part of the encoded string, i.e. <nnn> - <name>
+    found = false;
+    for (Int_t j=0; j<oarray->GetEntriesFast(); j++) {
+      p_ostr = dynamic_cast<TObjString*>(oarray->At(j));
+      if (p_ostr->GetString().BeginsWith(str)) { // present hence replace
+        oarray->AddAt(ostr.Clone(), j);
+        oarray->Write();
+        found = true;
+        break;
+      }
+    }
+    if (!found) {
+      oarray->AddLast(ostr.Clone());
+      oarray->Write();
+    }
+  }
 
   return true;
 }
@@ -899,7 +948,7 @@ Bool_t TMusrRunHeader::ExtractAll(TFolder *folder)
  *
  * \param dir
  */
-Bool_t TMusrRunHeader::ExtractAll(TDirectoryFile *dir)
+Bool_t TMusrRunHeader::ExtractAll(TDirectory *dir)
 {
   // NOT YET IMPLEMENTED
 
@@ -1558,6 +1607,50 @@ bool TMusrRunHeader::UpdateFolder(TObject *treeObj, TString path)
   }
 }
 
+//--------------------------------------------------------------------------
+// UpdateDirTree (private)
+//--------------------------------------------------------------------------
+/**
+ * <p>Update directory tree for RunHeader
+ *
+ * \param dir top directory pointer
+ *
+ * \return true on success, false otherwise
+ */
+bool TMusrRunHeader::UpdateDirTree(TDirectory *topdir)
+{
+  if (strcmp(topdir->GetName(), "RunHeader")) {
+    std::cerr << std::endl << ">> TMusrRunHeader::UpdateDirTree(): **ERROR** top dir has to be named RunHeader, found '" << topdir->GetName() << "' !" << std::endl;
+    return false;
+  }
+
+  TDirectory *dir;
+  TObjArray *tok = nullptr;
+  TObjString *ostr = nullptr;
+  TString tstr{""};
+  TObject *obj;
+  for (TString str : fPathNameOrder) { // loop through all path-names
+    dir = topdir;
+    if (tok != nullptr)
+      delete tok;
+    tok = str.Tokenize("/");
+    for (UInt_t i=0; i<tok->GetEntries(); i++) {
+      ostr = dynamic_cast<TObjString*>(tok->At(i));
+      tstr = ostr->GetString();
+      if (i != tok->GetEntries()-1) { // TDirectory
+        if ((obj = topdir->FindObjectAny(tstr.Data())) == nullptr) { // TDirectory new
+          TDirectory *ndir = dir->mkdir(tstr.Data());
+          dir = ndir;
+        } else { // TDirectory exists
+          dir = dynamic_cast<TDirectory*>(obj);
+        }
+      }
+    }
+  }
+
+  return true;
+}
+
 //--------------------------------------------------------------------------
 // FindObject (private)
 //--------------------------------------------------------------------------
diff --git a/src/external/MusrRoot/TMusrRunHeader.h b/src/external/MusrRoot/TMusrRunHeader.h
index 7456897c7..999122e0f 100644
--- a/src/external/MusrRoot/TMusrRunHeader.h
+++ b/src/external/MusrRoot/TMusrRunHeader.h
@@ -38,7 +38,7 @@
 #include <TObjString.h>
 #include <TObjArray.h>
 #include <TFolder.h>
-#include <TDirectoryFile.h>
+#include <TDirectory.h>
 
 #define MRH_UNDEFINED -9.99e99
 
@@ -130,10 +130,10 @@ public:
   virtual TString GetFileName() { return fFileName; }
 
   virtual Bool_t FillFolder(TFolder *folder);
-  virtual Bool_t FillDirectory(TDirectoryFile *dir);
+  virtual Bool_t FillDirectory(TDirectory *dir);
 
   virtual Bool_t ExtractAll(TFolder *folder);
-  virtual Bool_t ExtractAll(TDirectoryFile *folder);
+  virtual Bool_t ExtractAll(TDirectory *dir);
   virtual Bool_t ExtractHeaderInformation(TObjArray *headerInfo, TString path);
 
   virtual TString GetTypeOfPath(TString pathName);
@@ -186,6 +186,7 @@ private:
   virtual TString GetType(TString str);
 
   virtual bool UpdateFolder(TObject *treeObj, TString path);
+  virtual bool UpdateDirTree(TDirectory *topdir);
   virtual TObject* FindObject(TObject *treeObj, TString path);
   virtual TObjString GetHeaderString(UInt_t idx);