diff --git a/tests/periph_uart_nonblocking/main.c b/tests/periph_uart_nonblocking/main.c
index 62e2f6fabb..d5e1bbf631 100644
--- a/tests/periph_uart_nonblocking/main.c
+++ b/tests/periph_uart_nonblocking/main.c
@@ -30,8 +30,21 @@ static inline uint32_t puts_delay(const char* str)
     return LINE_DELAY_MS * 1000;
 }
 
+static void _irq_disabled_print(void)
+{
+    unsigned state = irq_disable();
+    /* fill the transmit buffer */
+    for (uint8_t i = 0; i < UART_TXBUF_SIZE; i++) {
+        printf(" ");
+    }
+    puts("\nputs with disabled interrupts and a full transmit buffer");
+    irq_restore(state);
+}
+
 int main(void)
 {
+    _irq_disabled_print();
+
     uint32_t total_us = 0;
     xtimer_ticks32_t counter = xtimer_now();
 
diff --git a/tests/periph_uart_nonblocking/tests/01-run.py b/tests/periph_uart_nonblocking/tests/01-run.py
index 0a412e5086..028db2dcdf 100755
--- a/tests/periph_uart_nonblocking/tests/01-run.py
+++ b/tests/periph_uart_nonblocking/tests/01-run.py
@@ -14,6 +14,7 @@ PRECISION = 1.002
 
 
 def testfunc(child):
+    child.expect_exact("puts with disabled interrupts and a full transmit buffer")
     child.expect(r'== printed in (\d+)/(\d+) µs ==')
     time_actual = int(child.match.group(1))
     time_expect = int(child.match.group(2))