diff --git a/components/esp32/include/rom/uart.h b/components/esp32/include/rom/uart.h
index 81fa26c23..8f075392c 100644
--- a/components/esp32/include/rom/uart.h
+++ b/components/esp32/include/rom/uart.h
@@ -267,7 +267,7 @@ void uart_tx_flush(uint8_t uart_no);
   * The function defined in ROM code has a bug, so we define the correct version
   * here for compatibility.
   */
-static inline void uart_tx_wait_idle(uint8_t uart_no) {
+static inline void IRAM_ATTR uart_tx_wait_idle(uint8_t uart_no) {
     while(REG_GET_FIELD(UART_STATUS_REG(uart_no), UART_ST_UTX_OUT)) {
         ;
     }