diff --git a/a1/program.c b/a1/program.c
index 5c583b6..8609d97 100644
--- a/a1/program.c
+++ b/a1/program.c
@@ -22,7 +22,7 @@ int main()
         {
             putchar(tolower(vstup));
         }
-        else if (iscntrl(vstup) == 0)
+        else if (!iscntrl(vstup))
         {
             putchar(vstup);
         }