diff --git a/drivers/serial/uart_mcux.c b/drivers/serial/uart_mcux.c
index 703fc0db684..b62953df943 100644
--- a/drivers/serial/uart_mcux.c
+++ b/drivers/serial/uart_mcux.c
@@ -132,16 +132,17 @@ static int uart_mcux_irq_tx_complete(struct device *dev)
 	const struct uart_mcux_config *config = dev->config_info;
 	uint32_t flags = UART_GetStatusFlags(config->base);
 
-	return (flags & kUART_TxDataRegEmptyFlag) != 0U;
+	return (flags & kUART_TransmissionCompleteFlag) != 0U;
 }
 
 static int uart_mcux_irq_tx_ready(struct device *dev)
 {
 	const struct uart_mcux_config *config = dev->config_info;
 	uint32_t mask = kUART_TxDataRegEmptyInterruptEnable;
+	uint32_t flags = UART_GetStatusFlags(config->base);
 
 	return (UART_GetEnabledInterrupts(config->base) & mask)
-		&& uart_mcux_irq_tx_complete(dev);
+		&& (flags & kUART_TxDataRegEmptyFlag);
 }
 
 static void uart_mcux_irq_rx_enable(struct device *dev)
diff --git a/drivers/serial/uart_mcux_flexcomm.c b/drivers/serial/uart_mcux_flexcomm.c
index 88a92ba4fae..1924fd1c35e 100644
--- a/drivers/serial/uart_mcux_flexcomm.c
+++ b/drivers/serial/uart_mcux_flexcomm.c
@@ -142,18 +142,18 @@ static void mcux_flexcomm_irq_tx_disable(struct device *dev)
 static int mcux_flexcomm_irq_tx_complete(struct device *dev)
 {
 	const struct mcux_flexcomm_config *config = dev->config_info;
-	uint32_t flags = USART_GetStatusFlags(config->base);
 
-	return (flags & kUSART_TxFifoEmptyFlag) != 0U;
+	return (config->base->STAT & USART_STAT_TXIDLE_MASK) != 0;
 }
 
 static int mcux_flexcomm_irq_tx_ready(struct device *dev)
 {
 	const struct mcux_flexcomm_config *config = dev->config_info;
 	uint32_t mask = kUSART_TxLevelInterruptEnable;
+	uint32_t flags = USART_GetStatusFlags(config->base);
 
 	return (USART_GetEnabledInterrupts(config->base) & mask)
-		&& mcux_flexcomm_irq_tx_complete(dev);
+		&& (flags & kUSART_TxFifoEmptyFlag);
 }
 
 static void mcux_flexcomm_irq_rx_enable(struct device *dev)
diff --git a/drivers/serial/uart_mcux_lpsci.c b/drivers/serial/uart_mcux_lpsci.c
index 7e8d1fef10b..b7c2bc43f1d 100644
--- a/drivers/serial/uart_mcux_lpsci.c
+++ b/drivers/serial/uart_mcux_lpsci.c
@@ -134,16 +134,17 @@ static int mcux_lpsci_irq_tx_complete(struct device *dev)
 	const struct mcux_lpsci_config *config = dev->config_info;
 	uint32_t flags = LPSCI_GetStatusFlags(config->base);
 
-	return (flags & kLPSCI_TxDataRegEmptyFlag) != 0U;
+	return (flags & kLPSCI_TransmissionCompleteFlag) != 0U;
 }
 
 static int mcux_lpsci_irq_tx_ready(struct device *dev)
 {
 	const struct mcux_lpsci_config *config = dev->config_info;
 	uint32_t mask = kLPSCI_TxDataRegEmptyInterruptEnable;
+	uint32_t flags = LPSCI_GetStatusFlags(config->base);
 
 	return (LPSCI_GetEnabledInterrupts(config->base) & mask)
-		&& mcux_lpsci_irq_tx_complete(dev);
+		&& (flags & kLPSCI_TxDataRegEmptyFlag);
 }
 
 static void mcux_lpsci_irq_rx_enable(struct device *dev)