diff --git a/tests/driver_my9221/main.c b/tests/driver_my9221/main.c
index 96223591b1..54433f6ae7 100644
--- a/tests/driver_my9221/main.c
+++ b/tests/driver_my9221/main.c
@@ -51,7 +51,8 @@ int main(void)
         my9221_set_led(&dev, i, MY9221_LED_OFF);
     }
     xtimer_usleep(TEST_WAIT);
-    for (unsigned i=dev.params.leds; i > 0 ; --i) {
+    for (unsigned j=dev.params.leds; j > 0 ; --j) {
+        unsigned i = j-1;
         my9221_set_led(&dev, i, MY9221_LED_ON);
         xtimer_usleep(TEST_WAIT);
         my9221_set_led(&dev, i, MY9221_LED_OFF);