diff --git a/subjects/printchessboard.en.md b/subjects/printchessboard.en.md
index c4ac0644..eebbe8ec 100644
--- a/subjects/printchessboard.en.md
+++ b/subjects/printchessboard.en.md
@@ -16,5 +16,7 @@ student@ubuntu:~/[[ROOT]]/printchessboard$ ./printchessboard 4 3 | cat -e
 # # $
 student@ubuntu:~/[[ROOT]]/printchessboard$ ./printchessboard 7 | cat -e
 Error$
+student@ubuntu:~/[[ROOT]]/printchessboard$ ./printchessboard 0 0 | cat -e
+Error$
 student@ubuntu:~/[[ROOT]]/printchessboard$
 ```