diff --git a/a1/program.c b/a1/program.c
index 0bfdd5a..2800321 100644
--- a/a1/program.c
+++ b/a1/program.c
@@ -15,7 +15,7 @@ int main() {
         else if (i >= 'A' && i <= 'Z') {
             putchar(i - 'A' + 'a');
         }
-        else {
+        else if (i >= 32 && i <= 126) {
             putchar(i);
         }
     }