diff --git a/source/drivers/usart_console.c b/source/drivers/usart_console.c
index ef7122b..57f5deb 100644
--- a/source/drivers/usart_console.c
+++ b/source/drivers/usart_console.c
@@ -130,7 +130,7 @@ static ssize_t usart_write(void *cookie, const char *buf, size_t n)
 
 static int usart_get_irq_no(unsigned *irq_no, unsigned dev)
 {
-	if (irq_no)
+	if (!irq_no)
 		return -1;
 
 	switch (dev) {