diff --git a/tracking/monitors/monitors.py b/tracking/monitors/monitors.py
index 14ea801be0c7bd17bbd98bfd27991aaa60e378fe..e6234651dc30eed6693b8200f86ded7b96d7fbe9 100644
--- a/tracking/monitors/monitors.py
+++ b/tracking/monitors/monitors.py
@@ -148,7 +148,7 @@ class Monitor(Element, metaclass=ABCMeta):
         for key, value in dict_file.items():
             self.g.require_dataset(key, value, dtype=float)
         
-        # create a dictionary which 
+        # create a dictionary which handle slices
         slice_dict = {}
         for key, value in dict_file.items():
             slice_dict[key] = []
@@ -545,7 +545,7 @@ class ProfileMonitor(Monitor):
     Methods
     -------
     track(object_to_save)
-        Save data
+        Save data.
     """
     
     def __init__(self, bunch_number, dimensions="tau", n_bin=75, file_name=None, 
@@ -566,7 +566,7 @@ class ProfileMonitor(Monitor):
         
         dict_buffer = {}
         dict_file = {}
-        for index, dim in enumerate(dimensions):
+        for index, dim in enumerate(self.dimensions):
             dict_buffer.update({dim : (self.n_bin[index], buffer_size)})
             dict_buffer.update({dim + "_bin" : (self.n_bin[index] + 1, buffer_size)})
             dict_file.update({dim : (self.n_bin[index], total_size)})