diff --git a/pysqm/plot.py b/pysqm/plot.py
index 1e0041ccc6108bb2aa9919e29221ac918cd934bd..f411e28c9b31f3d3eca4fe86831db40f233e3289 100644
--- a/pysqm/plot.py
+++ b/pysqm/plot.py
@@ -805,7 +805,7 @@ def make_plot(input_filename=None,send_emails=False,write_stats=False):
 
     if (input_filename is None):
         input_filename  = config.current_data_directory+\
-         '/'+config._device_shorttype+'_'+config._observatory_name+'.dat'
+         '/'+config._device_shorttype+'_'+config._observatory_name+'.txt'
 
     # Define the observatory in ephem
     Ephem = Ephemerids()
diff --git a/pysqm/read.py b/pysqm/read.py
index 716319250d92271ae4d10b773c92fb2c4a14455d..fbcdc0e0043b391c72f025be0b38b7523f9fc453 100644
--- a/pysqm/read.py
+++ b/pysqm/read.py
@@ -191,13 +191,13 @@ class device(observatory):
 
         self.monthly_datafile = \
          config.monthly_data_directory+"/"+yearmonth+"_"+\
-         config._device_shorttype+"_"+config._observatory_name+".dat"
+         config._device_shorttype+"_"+config._observatory_name+".txt"
         self.daily_datafile = \
          config.daily_data_directory+"/"+yearmonth+"/"+\
-         yearmonthday+"_"+config._device_shorttype+"_"+config._observatory_name+'.dat'
+         yearmonthday+"_"+config._device_shorttype+"_"+config._observatory_name+'.txt'
         self.current_datafile = \
          config.current_data_directory+"/"+config._device_shorttype+\
-         "_"+config._observatory_name+".dat"
+         "_"+config._observatory_name+".txt"
 
     def save_data(self,formatted_data):
         '''