diff --git a/targets/TARGET_NUVOTON/TARGET_M2351/serial_api.c b/targets/TARGET_NUVOTON/TARGET_M2351/serial_api.c
index 47e878062e..2cc458d501 100644
--- a/targets/TARGET_NUVOTON/TARGET_M2351/serial_api.c
+++ b/targets/TARGET_NUVOTON/TARGET_M2351/serial_api.c
@@ -85,9 +85,10 @@ static void serial_rx_enable_event(serial_t *obj, int event, uint8_t enable);
 static int serial_is_rx_complete(serial_t *obj);
 
 static void serial_check_dma_usage(DMAUsage *dma_usage, int *dma_ch);
-static int serial_is_irq_en(serial_t *obj, SerialIrq irq);
 #endif
 
+static int serial_is_irq_en(serial_t *obj, SerialIrq irq);
+
 bool serial_can_deep_sleep(void);
 
 static struct nu_uart_var uart0_var = {
@@ -531,7 +532,8 @@ static void uart_irq(serial_t *obj)
     if (uart_base->INTSTS & (UART_INTSTS_RDAINT_Msk | UART_INTSTS_RXTOINT_Msk)) {
         // Simulate clear of the interrupt flag. Temporarily disable the interrupt here and to be recovered on next read.
         UART_DISABLE_INT(uart_base, (UART_INTEN_RDAIEN_Msk | UART_INTEN_RXTOIEN_Msk));
-        if (obj->serial.irq_handler) {
+        if (obj->serial.irq_handler && serial_is_irq_en(obj, RxIrq)) {
+            // Call irq_handler() only when RxIrq is enabled
             ((uart_irq_handler) obj->serial.irq_handler)(obj->serial.irq_id, RxIrq);
         }
     }
@@ -539,7 +541,8 @@ static void uart_irq(serial_t *obj)
     if (uart_base->INTSTS & UART_INTSTS_THREINT_Msk) {
         // Simulate clear of the interrupt flag. Temporarily disable the interrupt here and to be recovered on next write.
         UART_DISABLE_INT(uart_base, UART_INTEN_THREIEN_Msk);
-        if (obj->serial.irq_handler) {
+        if (obj->serial.irq_handler && serial_is_irq_en(obj, TxIrq)) {
+            // Call irq_handler() only when TxIrq is enabled
             ((uart_irq_handler) obj->serial.irq_handler)(obj->serial.irq_id, TxIrq);
         }
     }
@@ -1179,6 +1182,8 @@ static void serial_check_dma_usage(DMAUsage *dma_usage, int *dma_ch)
     }
 }
 
+#endif  // #if DEVICE_SERIAL_ASYNCH
+
 static int serial_is_irq_en(serial_t *obj, SerialIrq irq)
 {
     int inten_msk = 0;
@@ -1195,8 +1200,6 @@ static int serial_is_irq_en(serial_t *obj, SerialIrq irq)
     return !! inten_msk;
 }
 
-#endif  // #if DEVICE_SERIAL_ASYNCH
-
 bool serial_can_deep_sleep(void)
 {
     bool sleep_allowed = 1;
diff --git a/targets/TARGET_NUVOTON/TARGET_M451/serial_api.c b/targets/TARGET_NUVOTON/TARGET_M451/serial_api.c
index 7ff9ca6ff7..d361d68ca4 100644
--- a/targets/TARGET_NUVOTON/TARGET_M451/serial_api.c
+++ b/targets/TARGET_NUVOTON/TARGET_M451/serial_api.c
@@ -81,9 +81,10 @@ static void serial_rx_enable_event(serial_t *obj, int event, uint8_t enable);
 static int serial_is_rx_complete(serial_t *obj);
 
 static void serial_check_dma_usage(DMAUsage *dma_usage, int *dma_ch);
-static int serial_is_irq_en(serial_t *obj, SerialIrq irq);
 #endif
 
+static int serial_is_irq_en(serial_t *obj, SerialIrq irq);
+
 bool serial_can_deep_sleep(void);
 
 static struct nu_uart_var uart0_var = {
@@ -464,7 +465,8 @@ static void uart_irq(serial_t *obj)
     if (uart_base->INTSTS & (UART_INTSTS_RDAINT_Msk | UART_INTSTS_RXTOINT_Msk)) {
         // Simulate clear of the interrupt flag. Temporarily disable the interrupt here and to be recovered on next read.
         UART_DISABLE_INT(uart_base, (UART_INTEN_RDAIEN_Msk | UART_INTEN_RXTOIEN_Msk));
-        if (obj->serial.irq_handler) {
+        if (obj->serial.irq_handler && serial_is_irq_en(obj, RxIrq)) {
+            // Call irq_handler() only when RxIrq is enabled
             ((uart_irq_handler) obj->serial.irq_handler)(obj->serial.irq_id, RxIrq);
         }
     }
@@ -472,7 +474,8 @@ static void uart_irq(serial_t *obj)
     if (uart_base->INTSTS & UART_INTSTS_THREINT_Msk) {
         // Simulate clear of the interrupt flag. Temporarily disable the interrupt here and to be recovered on next write.
         UART_DISABLE_INT(uart_base, UART_INTEN_THREIEN_Msk);
-        if (obj->serial.irq_handler) {
+        if (obj->serial.irq_handler && serial_is_irq_en(obj, TxIrq)) {
+            // Call irq_handler() only when TxIrq is enabled
             ((uart_irq_handler) obj->serial.irq_handler)(obj->serial.irq_id, TxIrq);
         }
     }
@@ -1102,6 +1105,8 @@ static void serial_check_dma_usage(DMAUsage *dma_usage, int *dma_ch)
     }
 }
 
+#endif  // #if DEVICE_SERIAL_ASYNCH
+
 static int serial_is_irq_en(serial_t *obj, SerialIrq irq)
 {
     int inten_msk = 0;
@@ -1118,8 +1123,6 @@ static int serial_is_irq_en(serial_t *obj, SerialIrq irq)
     return !! inten_msk;
 }
 
-#endif  // #if DEVICE_SERIAL_ASYNCH
-
 bool serial_can_deep_sleep(void)
 {
     bool sleep_allowed = 1;
diff --git a/targets/TARGET_NUVOTON/TARGET_M480/serial_api.c b/targets/TARGET_NUVOTON/TARGET_M480/serial_api.c
index 6a69e06c71..cfdc75bdcd 100644
--- a/targets/TARGET_NUVOTON/TARGET_M480/serial_api.c
+++ b/targets/TARGET_NUVOTON/TARGET_M480/serial_api.c
@@ -85,9 +85,10 @@ static void serial_rx_enable_event(serial_t *obj, int event, uint8_t enable);
 static int serial_is_rx_complete(serial_t *obj);
 
 static void serial_check_dma_usage(DMAUsage *dma_usage, int *dma_ch);
-static int serial_is_irq_en(serial_t *obj, SerialIrq irq);
 #endif
 
+static int serial_is_irq_en(serial_t *obj, SerialIrq irq);
+
 bool serial_can_deep_sleep(void);
 
 static struct nu_uart_var uart0_var = {
@@ -519,7 +520,8 @@ static void uart_irq(serial_t *obj)
     if (uart_base->INTSTS & (UART_INTSTS_RDAINT_Msk | UART_INTSTS_RXTOINT_Msk)) {
         // Simulate clear of the interrupt flag. Temporarily disable the interrupt here and to be recovered on next read.
         UART_DISABLE_INT(uart_base, (UART_INTEN_RDAIEN_Msk | UART_INTEN_RXTOIEN_Msk));
-        if (obj->serial.irq_handler) {
+        if (obj->serial.irq_handler && serial_is_irq_en(obj, RxIrq)) {
+            // Call irq_handler() only when RxIrq is enabled
             ((uart_irq_handler) obj->serial.irq_handler)(obj->serial.irq_id, RxIrq);
         }
     }
@@ -527,7 +529,8 @@ static void uart_irq(serial_t *obj)
     if (uart_base->INTSTS & UART_INTSTS_THREINT_Msk) {
         // Simulate clear of the interrupt flag. Temporarily disable the interrupt here and to be recovered on next write.
         UART_DISABLE_INT(uart_base, UART_INTEN_THREIEN_Msk);
-        if (obj->serial.irq_handler) {
+        if (obj->serial.irq_handler && serial_is_irq_en(obj, TxIrq)) {
+            // Call irq_handler() only when TxIrq is enabled
             ((uart_irq_handler) obj->serial.irq_handler)(obj->serial.irq_id, TxIrq);
         }
     }
@@ -1154,6 +1157,8 @@ static void serial_check_dma_usage(DMAUsage *dma_usage, int *dma_ch)
     }
 }
 
+#endif  // #if DEVICE_SERIAL_ASYNCH
+
 static int serial_is_irq_en(serial_t *obj, SerialIrq irq)
 {
     int inten_msk = 0;
@@ -1170,8 +1175,6 @@ static int serial_is_irq_en(serial_t *obj, SerialIrq irq)
     return !! inten_msk;
 }
 
-#endif  // #if DEVICE_SERIAL_ASYNCH
-
 bool serial_can_deep_sleep(void)
 {
     bool sleep_allowed = 1;
diff --git a/targets/TARGET_NUVOTON/TARGET_NANO100/serial_api.c b/targets/TARGET_NUVOTON/TARGET_NANO100/serial_api.c
index df19c2f8a5..3cc41eca42 100644
--- a/targets/TARGET_NUVOTON/TARGET_NANO100/serial_api.c
+++ b/targets/TARGET_NUVOTON/TARGET_NANO100/serial_api.c
@@ -74,9 +74,10 @@ static void serial_rx_enable_event(serial_t *obj, int event, uint8_t enable);
 static int serial_is_rx_complete(serial_t *obj);
 
 static void serial_check_dma_usage(DMAUsage *dma_usage, int *dma_ch);
-static int serial_is_irq_en(serial_t *obj, SerialIrq irq);
 #endif
 
+static int serial_is_irq_en(serial_t *obj, SerialIrq irq);
+
 bool serial_can_deep_sleep(void);
 
 static struct nu_uart_var uart0_var = {
@@ -426,7 +427,8 @@ static void uart_irq(serial_t *obj)
     if (uart_base->ISR & (UART_ISR_RDA_IS_Msk | UART_ISR_RTO_IS_Msk)) {
         // Simulate clear of the interrupt flag. Temporarily disable the interrupt here and to be recovered on next read.
         UART_DISABLE_INT(uart_base, (UART_IER_RDA_IE_Msk | UART_IER_RTO_IE_Msk));
-        if (obj->serial.irq_handler) {
+        if (obj->serial.irq_handler && serial_is_irq_en(obj, RxIrq)) {
+            // Call irq_handler() only when RxIrq is enabled
             ((uart_irq_handler) obj->serial.irq_handler)(obj->serial.irq_id, RxIrq);
         }
     }
@@ -434,7 +436,8 @@ static void uart_irq(serial_t *obj)
     if (uart_base->ISR & UART_ISR_THRE_IS_Msk) {
         // Simulate clear of the interrupt flag. Temporarily disable the interrupt here and to be recovered on next write.
         UART_DISABLE_INT(uart_base, UART_IER_THRE_IE_Msk);
-        if (obj->serial.irq_handler) {
+        if (obj->serial.irq_handler && serial_is_irq_en(obj, TxIrq)) {
+            // Call irq_handler() only when TxIrq is enabled
             ((uart_irq_handler) obj->serial.irq_handler)(obj->serial.irq_id, TxIrq);
         }
     }
@@ -1003,6 +1006,8 @@ static void serial_check_dma_usage(DMAUsage *dma_usage, int *dma_ch)
     }
 }
 
+#endif  // #if DEVICE_SERIAL_ASYNCH
+
 static int serial_is_irq_en(serial_t *obj, SerialIrq irq)
 {
     int ier_msk = 0;
@@ -1019,8 +1024,6 @@ static int serial_is_irq_en(serial_t *obj, SerialIrq irq)
     return !! ier_msk;
 }
 
-#endif  // #if DEVICE_SERIAL_ASYNCH
-
 bool serial_can_deep_sleep(void)
 {
     bool sleep_allowed = 1;
diff --git a/targets/TARGET_NUVOTON/TARGET_NUC472/serial_api.c b/targets/TARGET_NUVOTON/TARGET_NUC472/serial_api.c
index 65d21697d1..c21b65eb39 100644
--- a/targets/TARGET_NUVOTON/TARGET_NUC472/serial_api.c
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/serial_api.c
@@ -85,9 +85,10 @@ static void serial_rx_enable_event(serial_t *obj, int event, uint8_t enable);
 static int serial_is_rx_complete(serial_t *obj);
 
 static void serial_check_dma_usage(DMAUsage *dma_usage, int *dma_ch);
-static int serial_is_irq_en(serial_t *obj, SerialIrq irq);
 #endif
 
+static int serial_is_irq_en(serial_t *obj, SerialIrq irq);
+
 bool serial_can_deep_sleep(void);
 
 static struct nu_uart_var uart0_var = {
@@ -504,7 +505,8 @@ static void uart_irq(serial_t *obj)
     if (uart_base->INTSTS & (UART_INTSTS_RDAINT_Msk | UART_INTSTS_RXTOINT_Msk)) {
         // Simulate clear of the interrupt flag. Temporarily disable the interrupt here and to be recovered on next read.
         UART_DISABLE_INT(uart_base, (UART_INTEN_RDAIEN_Msk | UART_INTEN_RXTOIEN_Msk));
-        if (obj->serial.irq_handler) {
+        if (obj->serial.irq_handler && serial_is_irq_en(obj, RxIrq)) {
+            // Call irq_handler() only when RxIrq is enabled
             ((uart_irq_handler) obj->serial.irq_handler)(obj->serial.irq_id, RxIrq);
         }
     }
@@ -512,7 +514,8 @@ static void uart_irq(serial_t *obj)
     if (uart_base->INTSTS & UART_INTSTS_THREINT_Msk) {
         // Simulate clear of the interrupt flag. Temporarily disable the interrupt here and to be recovered on next write.
         UART_DISABLE_INT(uart_base, UART_INTEN_THREIEN_Msk);
-        if (obj->serial.irq_handler) {
+        if (obj->serial.irq_handler && serial_is_irq_en(obj, TxIrq)) {
+            // Call irq_handler() only when TxIrq is enabled
             ((uart_irq_handler) obj->serial.irq_handler)(obj->serial.irq_id, TxIrq);
         }
     }
@@ -1148,6 +1151,8 @@ static void serial_check_dma_usage(DMAUsage *dma_usage, int *dma_ch)
     }
 }
 
+#endif  // #if DEVICE_SERIAL_ASYNCH
+
 static int serial_is_irq_en(serial_t *obj, SerialIrq irq)
 {
     int inten_msk = 0;
@@ -1164,8 +1169,6 @@ static int serial_is_irq_en(serial_t *obj, SerialIrq irq)
     return !! inten_msk;
 }
 
-#endif  // #if DEVICE_SERIAL_ASYNCH
-
 bool serial_can_deep_sleep(void)
 {
     bool sleep_allowed = 1;