diff --git a/components/esp_driver_uart/src/uart.c b/components/esp_driver_uart/src/uart.c
index 5a842774cc4..2f08241e96f 100644
--- a/components/esp_driver_uart/src/uart.c
+++ b/components/esp_driver_uart/src/uart.c
@@ -1640,10 +1640,12 @@ static int uart_tx_all(uart_port_t uart_num, const char *src, size_t size, bool
         while (size > 0) {
             size_t free_size = xRingbufferGetCurFreeSize(p_uart_obj[uart_num]->tx_ring_buf);
             size_t send_size = MIN(size, free_size);
-            xRingbufferSend(p_uart_obj[uart_num]->tx_ring_buf, (void *)(src + offset), send_size, portMAX_DELAY);
-            size -= send_size;
-            offset += send_size;
-            uart_enable_tx_intr(uart_num, 1, UART_THRESHOLD_NUM(uart_num, UART_EMPTY_THRESH_DEFAULT));
+            if (send_size > 0) {
+                xRingbufferSend(p_uart_obj[uart_num]->tx_ring_buf, (void *)(src + offset), send_size, portMAX_DELAY);
+                size -= send_size;
+                offset += send_size;
+                uart_enable_tx_intr(uart_num, 1, UART_THRESHOLD_NUM(uart_num, UART_EMPTY_THRESH_DEFAULT));
+            }
         }
     } else {
         while (size) {
diff --git a/components/esp_driver_uart/test_apps/uart/main/test_uart.c b/components/esp_driver_uart/test_apps/uart/main/test_uart.c
index 17194cbd8a6..744aed019f0 100644
--- a/components/esp_driver_uart/test_apps/uart/main/test_uart.c
+++ b/components/esp_driver_uart/test_apps/uart/main/test_uart.c
@@ -440,7 +440,7 @@ TEST_CASE("uart tx ring buffer free space test", "[uart]")
         uart_port_t uart_num = port_param.port_num;
         uint8_t *rd_data = (uint8_t *)malloc(1024);
         TEST_ASSERT_NOT_NULL(rd_data);
-        uint8_t *wr_data = (uint8_t *)malloc(256);
+        uint8_t *wr_data = (uint8_t *)malloc(2048);
         TEST_ASSERT_NOT_NULL(wr_data);
         uart_config_t uart_config = {
             .baud_rate = 2000000,
@@ -475,7 +475,7 @@ TEST_CASE("uart tx ring buffer free space test", "[uart]")
         TEST_ASSERT_EQUAL_INT(0, tx_buffer_free_space); // tx buffer is full
 
         // Let CTS be low, so that transmission is unblocked
-        esp_rom_gpio_connect_in_signal(GPIO_MATRIX_CONST_ONE_INPUT, uart_periph_signal[uart_num].pins[SOC_UART_PERIPH_SIGNAL_CTS].signal, true);
+        esp_rom_gpio_connect_in_signal(GPIO_MATRIX_CONST_ZERO_INPUT, uart_periph_signal[uart_num].pins[SOC_UART_PERIPH_SIGNAL_CTS].signal, false);
         uart_wait_tx_done(uart_num, portMAX_DELAY);
         uart_get_tx_buffer_free_size(uart_num, &tx_buffer_free_space);
         TEST_ASSERT_EQUAL_INT(2020, tx_buffer_free_space); // tx buffer is back to full capacity