diff --git a/arch/sim/src/sim/sim_uart.c b/arch/sim/src/sim/sim_uart.c
index 3965b45a2a..604895a047 100644
--- a/arch/sim/src/sim/sim_uart.c
+++ b/arch/sim/src/sim/sim_uart.c
@@ -473,6 +473,11 @@ static void tty_txint(struct uart_dev_s *dev, bool enable)
   struct tty_priv_s *priv = dev->priv;
 
   priv->txint = enable;
+
+  if (enable)
+    {
+      uart_xmitchars(dev);
+    }
 }
 
 /****************************************************************************