Prevent printing non-existent short options in usage statement

1 files changed, 1 insertions, 1 deletions

diff --git a/src/main.c b/src/main.c
index b97b086..ed24287 100644
--- a/src/main.c
+++ b/src/main.c
@@ -89,7 +89,7 @@ static void usage(char *progname) {
     printf("usage: %s ", progname);
     printf("[-");
     for (int x = 0; long_options[x].val != 0; x++) {
-        if (long_options[x].has_arg == no_argument) {
+        if (long_options[x].has_arg == no_argument && long_options[x].val <= 'z') {
             putchar(long_options[x].val);
         }
     }