diff --git a/du4/program.c b/du4/program.c
index 64958ed..4bc46de 100644
--- a/du4/program.c
+++ b/du4/program.c
@@ -64,13 +64,13 @@ int main(){
                 printf("%s\n", (strtof(number1, &ptr) + strtof(number2, &ptr) == strtof(result, &ptr)) ? "OK" : "ZLE");
                 break;
             case 2:
-                printf("%s\n", strtof(number1, &ptr) - strtof(number2, &ptr) == strtof(result, &ptr)) ? "OK" : "ZLE");
+                printf("%s\n", (strtof(number1, &ptr) - strtof(number2, &ptr) == strtof(result, &ptr)) ? "OK" : "ZLE");
                 break;
             case 3:
-                printf("%s\n", strtof(number1, &ptr) * strtof(number2, &ptr) == strtof(result, &ptr)) ? "OK" : "ZLE");
+                printf("%s\n", (strtof(number1, &ptr) * strtof(number2, &ptr) == strtof(result, &ptr)) ? "OK" : "ZLE");
                 break;
             case 4:
-                printf("%s\n", strtof(number1, &ptr) / strtof(number2, &ptr) == strtof(result, &ptr)) ? "OK" : "ZLE");
+                printf("%s\n", (strtof(number1, &ptr) / strtof(number2, &ptr) == strtof(result, &ptr)) ? "OK" : "ZLE");
                 break;
             default:
                 printf("CHYBA");