diff --git a/src/project.cpp b/src/project.cpp
index f6f2281..25545ad 100644
--- a/src/project.cpp
+++ b/src/project.cpp
@@ -94,6 +94,9 @@ void ProjectList::save(std::string file_name){
     if (!of){
         std::cout << "Could not open file " << file_name << " for writing!" << std::endl;
     }
+    size_t month_len = month.length();
+    of.write((char*) &month_len, sizeof(size_t));
+    of.write((char*) month.c_str(), month_len);
     of.write((char*) &num_projects, sizeof(int));
     of.write((char*) &active_project_id, sizeof(int));
     for (int i=0; i<num_projects; i++){
@@ -113,12 +116,24 @@ void ProjectList::save(std::string file_name){
 }
 
 // reads project list from binary file
-void ProjectList::load(std::string file_name, bool ignore_worktimes){
+void ProjectList::load(std::string file_name, bool ignore_worktimes, bool legacy_mode){
     std::ifstream inf(file_name, std::ios::binary);
     int active;
     if (!inf){
         std::cout << "Could not open file " << file_name << " for reading!" << std::endl;
     }
+    size_t month_len;
+
+    if (!legacy_mode){
+        // read month string from file
+        inf.read((char*) &month_len,sizeof(size_t));
+        char *month_tmp = new char[month_len+1];
+        inf.read(month_tmp,month_len);
+        month_tmp[month_len] = '\0';
+        month = month_tmp;
+        delete [] month_tmp;
+    }
+
     inf.read((char*) &num_projects,sizeof(int));
     // save copy of num_projects to control loop and apply later as
     // num_projects will get bigger when adding projects to the project list
diff --git a/src/project.h b/src/project.h
index ab47439..e4c4708 100644
--- a/src/project.h
+++ b/src/project.h
@@ -33,7 +33,7 @@ class ProjectList{
         Project *active_project;
         void set_active_project(int id);
         void save(std::string file_name);
-        void load(std::string file_name, bool ignore_worktimes=false);
+        void load(std::string file_name, bool ignore_worktimes=false, bool legacy_mode=false);
         Project *find_project_by_name(std::string proj_name);
         int find_project_id_by_name(std::string proj_name); 
 };
diff --git a/src/ui.cpp b/src/ui.cpp
index 8fb41a1..3ee1730 100644
--- a/src/ui.cpp
+++ b/src/ui.cpp
@@ -588,7 +588,17 @@ void command_report(std::string date_str, ProjectList* proj_list){
     }else{
         ProjectList list(month);
         std::string file_name = tracking_dir+"/"+date_str;
-        list.load(file_name);
+        // legacy support for old tracking file format prior to version 1.3.0
+        // to be dropped with next major release
+        if (std::stoi(year) <= 2022 && std::stoi(month) <= 4){
+            std::cout << "Warning: possibly reading old data file of tt v.<1.3.0." << std::endl; 
+            std::cout << "Support for these files will be dropped with the next major release!" << std::endl;
+            std::cout << "Consider convertig them using the convert command." << std::endl << std::endl;
+            list.load(file_name,false, true);
+        }else{
+            list.load(file_name);
+        }
+        
         if (list.num_projects > 0){
             std::cout << "Report for " << user_name << ", month: " << date_str <<  std::endl << std::endl;
             for (int i=0; i<list.num_projects; i++){
@@ -614,8 +624,7 @@ void command_report(std::string date_str, ProjectList* proj_list){
 // save project list to file, uses system("mkdir") to create diretory
 // might be replaced by C++ filesystem API int the future
 void command_save(ProjectList *proj_list){
-    std::string date_str = get_date();
-    std::string file_name = tracking_dir+"/"+date_str;
+    std::string file_name = tracking_dir+"/"+proj_list->month;
     std::string command = "mkdir -p "+tracking_dir;
     system (command.c_str());
     proj_list->save(file_name);