diff --git a/ex13.c b/ex13.c
index dd086fb..10c6789 100644
--- a/ex13.c
+++ b/ex13.c
@@ -11,7 +11,7 @@ int main(int argc, char *argv[])
     for(i = 0; argv[1][i] != '\0'; i++) {
         char letter = argv[1][i];
 
-        switch(letter) {
+        switch(127 + (int)letter) {
             case 'a':
             case 'A':
                 printf("%d: 'A'\n", i);