diff --git a/bsp/samd21/applications/application.c b/bsp/samd21/applications/application.c
index a8ff004e380dee7ab68248c0995f68617b4e709a..186ee8ac4a2808b3f51801d00f82d652f4acac55 100644
--- a/bsp/samd21/applications/application.c
+++ b/bsp/samd21/applications/application.c
@@ -87,7 +87,7 @@ void rt_init_thread_entry(void* parameter)
     configure_extint_channel();
     configure_extint_callbacks();
 
-#if defined(TEST_UART_RX)
+#ifndef TEST_UART_RX
 
     sleep_timer_init();
 	// sleep_timer_start(1500);