diff --git a/targets/TARGET_STM/TARGET_STM32G0/serial_device.c b/targets/TARGET_STM/TARGET_STM32G0/serial_device.c
index c5f936b06bb..f436f95cde0 100644
--- a/targets/TARGET_STM/TARGET_STM32G0/serial_device.c
+++ b/targets/TARGET_STM/TARGET_STM32G0/serial_device.c
@@ -19,32 +19,27 @@
 
 #if defined (STM32G030xx) || defined (STM32G050xx)
 #define UART_NUM (2)
+#define USART_GROUP1_IRQn USART2_IRQn
 #elif defined (STM32G031xx) || defined (STM32G041xx) || defined (STM32G051xx) || defined (STM32G061xx)
 #define UART_NUM (3)
+#define USART_GROUP1_IRQn USART2_IRQn
+#define USART_GROUP2_IRQn LPUART1_IRQn
 #elif defined (STM32G070xx)
 #define UART_NUM (4)
-#define USART3_IRQn USART3_4_IRQn
-#define USART4_IRQn USART3_4_IRQn
+#define USART_GROUP1_IRQn USART2_IRQn
+#define USART_GROUP2_IRQn USART3_4_IRQn
 #elif defined (STM32G071xx) || defined (STM32G081xx)
 #define UART_NUM (5)
-#define USART3_IRQn USART3_4_LPUART1_IRQn
-#define USART4_IRQn USART3_4_LPUART1_IRQn
-#define LPUART1_IRQn USART3_4_LPUART1_IRQn
+#define USART_GROUP1_IRQn USART2_IRQn
+#define USART_GROUP2_IRQn USART3_4_LPUART1_IRQn
 #elif defined (STM32G0B0xx)
 #define UART_NUM (6)
-#define USART3_IRQn USART3_4_5_6_IRQn
-#define USART4_IRQn USART3_4_5_6_IRQn
-#define USART5_IRQn USART3_4_5_6_IRQn
-#define USART6_IRQn USART3_4_5_6_IRQn
+#define USART_GROUP1_IRQn USART2_IRQn
+#define USART_GROUP2_IRQn USART3_4_5_6_IRQn
 #elif defined (STM32G0B1xx) || defined (STM32G0C1xx)
 #define UART_NUM (8)
-#define USART2_IRQn USART2_LPUART2_IRQn
-#define USART3_IRQn USART3_4_5_6_LPUART1_IRQn
-#define USART4_IRQn USART3_4_5_6_LPUART1_IRQn
-#define USART5_IRQn USART3_4_5_6_LPUART1_IRQn
-#define USART6_IRQn USART3_4_5_6_LPUART1_IRQn
-#define LPUART1_IRQn USART3_4_5_6_LPUART1_IRQn
-#define LPUART2_IRQn USART2_LPUART2_IRQn
+#define USART_GROUP1_IRQn USART2_LPUART2_IRQn
+#define USART_GROUP2_IRQn USART3_4_5_6_LPUART1_IRQn
 #endif
 
 uint32_t serial_irq_ids[UART_NUM] = {0};
@@ -93,52 +88,36 @@ static void uart1_irq(void)
 }
 #endif
 
-#if defined(USART2_BASE)
-static void uart2_irq(void)
+#if defined (USART_GROUP1_IRQn)
+static void uart_group1_irq(void)
 {
+#if defined(USART2_BASE)
     uart_irq(UART_2);
+#endif
+#if defined(LPUART2_BASE)
+    uart_irq(LPUART_2);
+#endif
 }
 #endif
 
-#if defined(USART3_BASE)
-static void uart3_irq(void)
+#if defined(USART_GROUP2_IRQn)
+static void uart_group2_irq(void)
 {
+#if defined(USART3_BASE)
     uart_irq(UART_3);
-}
 #endif
-
 #if defined(USART4_BASE)
-static void uart4_irq(void)
-{
     uart_irq(UART_4);
-}
 #endif
-
 #if defined(USART5_BASE)
-static void uart5_irq(void)
-{
     uart_irq(UART_5);
-}
 #endif
-
 #if defined(USART6_BASE)
-static void uart6_irq(void)
-{
     uart_irq(UART_6);
-}
 #endif
-
 #if defined(LPUART1_BASE)
-static void lpuart1_irq(void)
-{
     uart_irq(LPUART_1);
-}
 #endif
-
-#if defined(LPUART2_BASE)
-static void lpuart2_irq(void)
-{
-    uart_irq(LPUART_2);
 }
 #endif
 
@@ -166,50 +145,50 @@ void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable)
 
 #if defined(USART2_BASE)
     if (obj_s->uart == UART_2) {
-        irq_n = USART2_IRQn;
-        vector = (uint32_t)&uart2_irq;
+        irq_n = USART_GROUP1_IRQn;
+        vector = (uint32_t)&uart_group1_irq;
     }
 #endif
 
 #if defined(USART3_BASE)
     if (obj_s->uart == UART_3) {
-        irq_n = USART3_IRQn;
-        vector = (uint32_t)&uart3_irq;
+        irq_n = USART_GROUP2_IRQn;
+        vector = (uint32_t)&uart_group2_irq;
     }
 #endif
 
 #if defined(USART4_BASE)
     if (obj_s->uart == UART_4) {
-        irq_n = USART4_IRQn;
-        vector = (uint32_t)&uart4_irq;
+        irq_n = USART_GROUP2_IRQn;
+        vector = (uint32_t)&uart_group2_irq;
     }
 #endif
 
 #if defined(USART5_BASE)
     if (obj_s->uart == UART_5) {
-        irq_n = USART5_IRQn;
-        vector = (uint32_t)&uart5_irq;
+        irq_n = USART_GROUP2_IRQn;
+        vector = (uint32_t)&uart_group2_irq;
     }
 #endif
 
 #if defined(USART6_BASE)
     if (obj_s->uart == UART_6) {
-        irq_n = USART6_IRQn;
-        vector = (uint32_t)&uart6_irq;
+        irq_n = USART_GROUP2_IRQn;
+        vector = (uint32_t)&uart_group2_irq;
     }
 #endif
 
 #if defined(LPUART1_BASE)
     if (obj_s->uart == LPUART_1) {
-        irq_n = LPUART1_IRQn;
-        vector = (uint32_t)&lpuart1_irq;
+        irq_n = USART_GROUP2_IRQn;
+        vector = (uint32_t)&uart_group2_irq;
     }
 #endif
 
 #if defined(LPUART2_BASE)
     if (obj_s->uart == LPUART_2) {
-        irq_n = LPUART2_IRQn;
-        vector = (uint32_t)&lpuart2_irq;
+        irq_n = USART_GROUP1_IRQn;
+        vector = (uint32_t)&uart_group1_irq;
     }
 #endif
 
@@ -382,37 +361,37 @@ static IRQn_Type serial_get_irq_n(UARTName uart_name)
 #endif
 #if defined(USART2_BASE)
         case UART_2:
-            irq_n = USART2_IRQn;
+            irq_n = USART_GROUP1_IRQn;
             break;
 #endif
 #if defined(USART3_BASE)
         case UART_3:
-            irq_n = USART3_IRQn;
+            irq_n = USART_GROUP2_IRQn;
             break;
 #endif
 #if defined(USART4_BASE)
         case UART_4:
-            irq_n = USART4_IRQn;
+            irq_n = USART_GROUP2_IRQn;
             break;
 #endif
 #if defined(USART5_BASE)
         case UART_5:
-            irq_n = USART5_IRQn;
+            irq_n = USART_GROUP2_IRQn;
             break;
 #endif
 #if defined(USART6_BASE)
         case UART_6:
-            irq_n = USART6_IRQn;
+            irq_n = USART_GROUP2_IRQn;
             break;
 #endif
 #if defined(LPUART1_BASE)
         case LPUART_1:
-            irq_n = LPUART1_IRQn;
+            irq_n = USART_GROUP2_IRQn;
             break;
 #endif
 #if defined(LPUART2_BASE)
         case LPUART_2:
-            irq_n = LPUART2_IRQn;
+            irq_n = USART_GROUP1_IRQn;
             break;
 #endif
         default:
diff --git a/targets/TARGET_STM/TARGET_STM32L0/serial_device.c b/targets/TARGET_STM/TARGET_STM32L0/serial_device.c
index 22e66ccd161..eb1927beaf7 100644
--- a/targets/TARGET_STM/TARGET_STM32L0/serial_device.c
+++ b/targets/TARGET_STM/TARGET_STM32L0/serial_device.c
@@ -79,17 +79,15 @@ static void uart2_irq(void)
 }
 #endif
 
-#if defined(USART4_BASE)
-static void uart4_irq(void)
+#if defined(USART4_BASE) || defined(USART5_BASE)
+static void uart4_5_irq(void)
 {
+#if defined(USART4_BASE)
     uart_irq(UART_4);
-}
 #endif
-
-#if defined(USART5_BASE)
-static void uart5_irq(void)
-{
+#if defined(USART4_BASE)
     uart_irq(UART_5);
+#endif
 }
 #endif
 
@@ -132,14 +130,14 @@ void serial_irq_set(serial_t *obj, SerialIrq irq, uint32_t enable)
 #if defined(USART4_BASE)
     if (obj_s->uart == UART_4) {
         irq_n = USART4_5_IRQn;
-        vector = (uint32_t)&uart4_irq;
+        vector = (uint32_t)&uart4_5_irq;
     }
 #endif
 
 #if defined(USART5_BASE)
     if (obj_s->uart == UART_5) {
         irq_n = USART4_5_IRQn;
-        vector = (uint32_t)&uart5_irq;
+        vector = (uint32_t)&uart4_5_irq;
     }
 #endif