diff --git a/README.md b/README.md
index cb0b357..ce18421 100644
--- a/README.md
+++ b/README.md
@@ -33,7 +33,7 @@ For the interstellar medium, the parameters star_radius, parsec and RF_list
 are no longer important; 
 the part of the program executed will be independent of them
 
-**three_levels_model.py** :  
+**four_levels_model.py** :  
 *Description* :  
 This main program computes the photoelectric heating rate and efficiency by PAHs. The expressions used are based on the model with 4 charge states of the molecule, going from the anion molecule (charge state Z=-1) to the dication (charge state Z=2) by ionization.  
 
@@ -56,7 +56,7 @@ This main program computes the photoelectric heating rate and efficiency by PAHs
             Interstellar Radiation Field; if true, then the filename is a file for ISRF
             if false, the radiation field of a star is studied (default: False)  
         
-        This program uses radiations_fields.py.   
+This program uses radiations_fields.py.   
 
 
 ## Useful files
--
libgit2 0.21.2