diff --git a/mbtrack2/tracking/monitors/monitors.py b/mbtrack2/tracking/monitors/monitors.py
index b1099fc588742bfa1d0577200121ca5f0d4d72f9..6d01794fdd4c289cfd775d141a0668f81f61cc2a 100644
--- a/mbtrack2/tracking/monitors/monitors.py
+++ b/mbtrack2/tracking/monitors/monitors.py
@@ -121,10 +121,10 @@ class Monitor(Element, metaclass=ABCMeta):
                 if len(self._file_storage) == 0:
                     if mpi_mode == True:
                         from mpi4py import MPI
-                        f = hp.File(self.file_name, "w", libver='earliest', 
+                        f = hp.File(self.file_name, "a", libver='earliest', 
                              driver='mpio', comm=MPI.COMM_WORLD)
                     else:
-                        f = hp.File(self.file_name, "w", libver='earliest')
+                        f = hp.File(self.file_name, "a", libver='earliest')
                     self._file_storage.append(f)
                 else:
                     raise ValueError("File is already open.")
@@ -669,7 +669,6 @@ class ProfileMonitor(Monitor):
                     self.write_count * self.buffer_size:(self.write_count+1) * 
                     self.buffer_size] = self.__getattribute__(dim + "_bin")
             
-        self.file.flush()
         self.write_count += 1
                     
     def track(self, object_to_save):