README.md in cumo-0.2.0 vs README.md in cumo-0.2.1

@@ -254,10 +254,10 @@
 
 You may want to show warnings everytime rather than once:
 
 ```
 export CUMO_SHOW_WARNING=ON
-export CUMO_WARNING_ONCE=OFF
+export CUMO_SHOW_WARNING_ONCE=OFF
 ```
 
 ## Contributing
 
 Bug reports and pull requests are welcome on GitHub at https://github.com/sonots/cumo.