diff --git a/os/hal/ports/STM32/LLD/USARTv2/hal_serial_lld.h b/os/hal/ports/STM32/LLD/USARTv2/hal_serial_lld.h
index 19ee3291c..3567c8d9d 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/hal_serial_lld.h
+++ b/os/hal/ports/STM32/LLD/USARTv2/hal_serial_lld.h
@@ -421,6 +421,79 @@
 #error "Invalid IRQ priority assigned to LPUART1"
 #endif
 
+/* Checks on allocation of USARTx units.*/
+#if STM32_SERIAL_USE_USART1
+#if defined(STM32_USART1_IS_USED)
+#error "SD1 requires USART1 but it is already used"
+#else
+#define STM32_USART1_IS_USED
+#endif
+#endif
+
+#if STM32_SERIAL_USE_USART2
+#if defined(STM32_USART2_IS_USED)
+#error "SD2 requires USART2 but it is already used"
+#else
+#define STM32_USART2_IS_USED
+#endif
+#endif
+
+#if STM32_SERIAL_USE_USART3
+#if defined(STM32_USART3_IS_USED)
+#error "SD3 requires USART3 but it is already used"
+#else
+#define STM32_USART3_IS_USED
+#endif
+#endif
+
+#if STM32_SERIAL_USE_UART4
+#if defined(STM32_UART4_IS_USED)
+#error "SD4 requires UART4 but it is already used"
+#else
+#define STM32_UART4_IS_USED
+#endif
+#endif
+
+#if STM32_SERIAL_USE_UART5
+#if defined(STM32_UART5_IS_USED)
+#error "SD5 requires UART5 but it is already used"
+#else
+#define STM32_UART5_IS_USED
+#endif
+#endif
+
+#if STM32_SERIAL_USE_USART6
+#if defined(STM32_USART6_IS_USED)
+#error "SD6 requires USART6 but it is already used"
+#else
+#define STM32_USART6_IS_USED
+#endif
+#endif
+
+#if STM32_SERIAL_USE_UART7
+#if defined(STM32_UART7_IS_USED)
+#error "SD7 requires UART7 but it is already used"
+#else
+#define STM32_UART7_IS_USED
+#endif
+#endif
+
+#if STM32_SERIAL_USE_UART8
+#if defined(STM32_UART8_IS_USED)
+#error "SD8 requires UART8 but it is already used"
+#else
+#define STM32_UART8_IS_USED
+#endif
+#endif
+
+#if STM32_SERIAL_USE_LPUART1
+#if defined(STM32_LPUART1_IS_USED)
+#error "LPSD1 requires LPUART1 but it is already used"
+#else
+#define STM32_LPUART1_IS_USED
+#endif
+#endif
+
 /*===========================================================================*/
 /* Driver data structures and types.                                         */
 /*===========================================================================*/
diff --git a/os/hal/ports/STM32/LLD/USARTv2/hal_uart_lld.h b/os/hal/ports/STM32/LLD/USARTv2/hal_uart_lld.h
index ec5a6949e..b7cac43d7 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/hal_uart_lld.h
+++ b/os/hal/ports/STM32/LLD/USARTv2/hal_uart_lld.h
@@ -613,6 +613,71 @@
 #define STM32_DMA_REQUIRED
 #endif
 
+/* Checks on allocation of USARTx units.*/
+#if STM32_UART_USE_USART1
+#if defined(STM32_USART1_IS_USED)
+#error "SD1 requires USART1 but it is already used"
+#else
+#define STM32_USART1_IS_USED
+#endif
+#endif
+
+#if STM32_UART_USE_USART2
+#if defined(STM32_USART2_IS_USED)
+#error "SD2 requires USART2 but it is already used"
+#else
+#define STM32_USART2_IS_USED
+#endif
+#endif
+
+#if STM32_UART_USE_USART3
+#if defined(STM32_USART3_IS_USED)
+#error "SD3 requires USART3 but it is already used"
+#else
+#define STM32_USART3_IS_USED
+#endif
+#endif
+
+#if STM32_UART_USE_UART4
+#if defined(STM32_UART4_IS_USED)
+#error "SD4 requires UART4 but it is already used"
+#else
+#define STM32_UART4_IS_USED
+#endif
+#endif
+
+#if STM32_UART_USE_UART5
+#if defined(STM32_UART5_IS_USED)
+#error "SD5 requires UART5 but it is already used"
+#else
+#define STM32_UART5_IS_USED
+#endif
+#endif
+
+#if STM32_UART_USE_USART6
+#if defined(STM32_USART6_IS_USED)
+#error "SD6 requires USART6 but it is already used"
+#else
+#define STM32_USART6_IS_USED
+#endif
+#endif
+
+#if STM32_UART_USE_UART7
+#if defined(STM32_UART7_IS_USED)
+#error "SD7 requires UART7 but it is already used"
+#else
+#define STM32_UART7_IS_USED
+#endif
+#endif
+
+#if STM32_UART_USE_UART8
+#if defined(STM32_UART8_IS_USED)
+#error "SD8 requires UART8 but it is already used"
+#else
+#define STM32_UART8_IS_USED
+#endif
+#endif
+
 /*===========================================================================*/
 /* Driver data structures and types.                                         */
 /*===========================================================================*/
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_lpuart1.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_lpuart1.inc
index 223ce2e12..14d880144 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_lpuart1.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_lpuart1.inc
@@ -48,13 +48,6 @@
 
 #endif /* STM32_HAS_LPUART1 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_LPUART1)
-#define STM32_LPUART1_IS_USED       TRUE
-#else
-#define STM32_LPUART1_IS_USED       FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -68,13 +61,13 @@
 /*===========================================================================*/
 
 static inline void lpuart1_irq_init(void) {
-#if STM32_LPUART1_IS_USED
+#if defined(STM32_LPUART1_IS_USED)
   nvicEnableVector(STM32_LPUART1_NUMBER, STM32_IRQ_LPUART1_PRIORITY);
 #endif
 }
 
 static inline void lpuart1_irq_deinit(void) {
-#if STM32_LPUART1_IS_USED
+#if defined(STM32_LPUART1_IS_USED)
   nvicDisableVector(STM32_LPUART1_NUMBER);
 #endif
 }
@@ -83,7 +76,7 @@ static inline void lpuart1_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_LPUART1_IS_USED || defined(__DOXYGEN__)
+#if defined(STM32_LPUART1_IS_USED) || defined(__DOXYGEN__)
 /**
  * @brief   LPUART1 interrupt handler.
  *
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_uart4.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_uart4.inc
index 5dd7b5101..fda09c310 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_uart4.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_uart4.inc
@@ -48,19 +48,6 @@
 
 #endif /* STM32_HAS_UART4 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART4) &&                           \
-    (HAL_USE_UART && STM32_UART_USE_UART4)
-#error "UART4 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART4) ||                           \
-    (HAL_USE_UART && STM32_UART_USE_UART4)
-#define STM32_UART4_IS_USED         TRUE
-#else
-#define STM32_UART4_IS_USED         FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -74,13 +61,13 @@
 /*===========================================================================*/
 
 static inline void uart4_irq_init(void) {
-#if STM32_UART4_IS_USED
+#if defined(STM32_UART4_IS_USED)
   nvicEnableVector(STM32_UART4_NUMBER, STM32_IRQ_UART4_PRIORITY);
 #endif
 }
 
 static inline void uart4_irq_deinit(void) {
-#if STM32_UART4_IS_USED
+#if defined(STM32_UART4_IS_USED)
   nvicDisableVector(STM32_UART4_NUMBER);
 #endif
 }
@@ -89,7 +76,7 @@ static inline void uart4_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_UART4_IS_USED || defined(__DOXYGEN__)
+#if defined(STM32_UART4_IS_USED) || defined(__DOXYGEN__)
 /**
  * @brief   UART4 interrupt handler.
  *
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_uart5.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_uart5.inc
index b382d849d..401294544 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_uart5.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_uart5.inc
@@ -48,19 +48,6 @@
 
 #endif /* STM32_HAS_UART5 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART5) &&                           \
-    (HAL_USE_UART && STM32_UART_USE_UART5)
-#error "UART5 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART5) ||                           \
-    (HAL_USE_UART && STM32_UART_USE_UART5)
-#define STM32_UART5_IS_USED         TRUE
-#else
-#define STM32_UART5_IS_USED         FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -74,13 +61,13 @@
 /*===========================================================================*/
 
 static inline void uart5_irq_init(void) {
-#if STM32_UART5_IS_USED
+#if defined(STM32_UART5_IS_USED)
   nvicEnableVector(STM32_UART5_NUMBER, STM32_IRQ_UART5_PRIORITY);
 #endif
 }
 
 static inline void uart5_irq_deinit(void) {
-#if STM32_UART5_IS_USED
+#if defined(STM32_UART5_IS_USED)
   nvicDisableVector(STM32_UART5_NUMBER);
 #endif
 }
@@ -89,7 +76,7 @@ static inline void uart5_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_UART5_IS_USED || defined(__DOXYGEN__)
+#if defined(STM32_UART5_IS_USED) || defined(__DOXYGEN__)
 /**
  * @brief   UART5 interrupt handler.
  *
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_uart7.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_uart7.inc
index 2ec791e35..a18ee75a1 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_uart7.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_uart7.inc
@@ -48,19 +48,6 @@
 
 #endif /* STM32_HAS_UART7 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART7) &&                           \
-    (HAL_USE_UART && STM32_UART_USE_UART7)
-#error "UART7 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART7) ||                           \
-    (HAL_USE_UART && STM32_UART_USE_UART7)
-#define STM32_UART7_IS_USED         TRUE
-#else
-#define STM32_UART7_IS_USED         FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -74,13 +61,13 @@
 /*===========================================================================*/
 
 static inline void uart7_irq_init(void) {
-#if STM32_UART7_IS_USED
+#if defined(STM32_UART7_IS_USED)
   nvicEnableVector(STM32_UART7_NUMBER, STM32_IRQ_UART7_PRIORITY);
 #endif
 }
 
 static inline void uart7_irq_deinit(void) {
-#if STM32_UART7_IS_USED
+#if defined(STM32_UART7_IS_USED)
   nvicDisableVector(STM32_UART7_NUMBER);
 #endif
 }
@@ -89,7 +76,7 @@ static inline void uart7_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_UART7_IS_USED || defined(__DOXYGEN__)
+#if defined(STM32_UART7_IS_USED) || defined(__DOXYGEN__)
 /**
  * @brief   UART7 interrupt handler.
  *
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_uart8.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_uart8.inc
index 89584318b..906d2a153 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_uart8.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_uart8.inc
@@ -48,19 +48,6 @@
 
 #endif /* STM32_HAS_UART8 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART8) &&                           \
-    (HAL_USE_UART && STM32_UART_USE_UART8)
-#error "UART8 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART8) ||                           \
-    (HAL_USE_UART && STM32_UART_USE_UART8)
-#define STM32_UART8_IS_USED         TRUE
-#else
-#define STM32_UART8_IS_USED         FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -74,13 +61,13 @@
 /*===========================================================================*/
 
 static inline void uart8_irq_init(void) {
-#if STM32_UART8_IS_USED
+#if defined(STM32_UART8_IS_USED)
   nvicEnableVector(STM32_UART8_NUMBER, STM32_IRQ_UART8_PRIORITY);
 #endif
 }
 
 static inline void uart8_irq_deinit(void) {
-#if STM32_UART8_IS_USED
+#if defined(STM32_UART8_IS_USED)
   nvicDisableVector(STM32_UART8_NUMBER);
 #endif
 }
@@ -89,7 +76,7 @@ static inline void uart8_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_UART8_IS_USED || defined(__DOXYGEN__)
+#if defined(STM32_UART8_IS_USED) || defined(__DOXYGEN__)
 /**
  * @brief   UART8 interrupt handler.
  *
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart1.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart1.inc
index 19aac1008..9d6b8b243 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart1.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart1.inc
@@ -48,19 +48,6 @@
 
 #endif /* STM32_HAS_USART1 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_USART1) &&                          \
-    (HAL_USE_UART && STM32_UART_USE_USART1)
-#error "USART1 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_USART1) ||                          \
-    (HAL_USE_UART && STM32_UART_USE_USART1)
-#define STM32_USART1_IS_USED        TRUE
-#else
-#define STM32_USART1_IS_USED        FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -74,13 +61,13 @@
 /*===========================================================================*/
 
 static inline void usart1_irq_init(void) {
-#if STM32_USART1_IS_USED
+#if defined(STM32_USART1_IS_USED)
   nvicEnableVector(STM32_USART1_NUMBER, STM32_IRQ_USART1_PRIORITY);
 #endif
 }
 
 static inline void usart1_irq_deinit(void) {
-#if STM32_USART1_IS_USED
+#if defined(STM32_USART1_IS_USED)
   nvicDisableVector(STM32_USART1_NUMBER);
 #endif
 }
@@ -89,7 +76,7 @@ static inline void usart1_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_USART1_IS_USED|| defined(__DOXYGEN__)
+#if defined(STM32_USART1_IS_USED) || defined(__DOXYGEN__)
 /**
  * @brief   USART1 interrupt handler.
  *
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart2.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart2.inc
index c4b900017..f7caebc87 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart2.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart2.inc
@@ -48,19 +48,6 @@
 
 #endif /* STM32_HAS_USART2 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_USART2) &&                          \
-    (HAL_USE_UART && STM32_UART_USE_USART2)
-#error "USART2 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_USART2) ||                          \
-    (HAL_USE_UART && STM32_UART_USE_USART2)
-#define STM32_USART2_IS_USED        TRUE
-#else
-#define STM32_USART2_IS_USED        FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -74,13 +61,13 @@
 /*===========================================================================*/
 
 static inline void usart2_irq_init(void) {
-#if STM32_USART2_IS_USED
+#if defined(STM32_USART2_IS_USED)
   nvicEnableVector(STM32_USART2_NUMBER, STM32_IRQ_USART2_PRIORITY);
 #endif
 }
 
 static inline void usart2_irq_deinit(void) {
-#if STM32_USART2_IS_USED
+#if defined(STM32_USART2_IS_USED)
   nvicDisableVector(STM32_USART2_NUMBER);
 #endif
 }
@@ -89,7 +76,7 @@ static inline void usart2_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_USART2_IS_USED || defined(__DOXYGEN__)
+#if defined(STM32_USART2_IS_USED) || defined(__DOXYGEN__)
 /**
  * @brief   USART2 interrupt handler.
  *
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart3.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart3.inc
index ff5dbda86..5fde3c7e0 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart3.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart3.inc
@@ -48,19 +48,6 @@
 
 #endif /* STM32_HAS_USART3 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_USART3) &&                          \
-    (HAL_USE_UART && STM32_UART_USE_USART3)
-#error "USART3 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_USART3) ||                          \
-    (HAL_USE_UART && STM32_UART_USE_USART3)
-#define STM32_USART3_IS_USED        TRUE
-#else
-#define STM32_USART3_IS_USED        FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -74,13 +61,13 @@
 /*===========================================================================*/
 
 static inline void usart3_irq_init(void) {
-#if STM32_USART3_IS_USED
+#if defined(STM32_USART3_IS_USED)
   nvicEnableVector(STM32_USART3_NUMBER, STM32_IRQ_USART3_PRIORITY);
 #endif
 }
 
 static inline void usart3_irq_deinit(void) {
-#if STM32_USART3_IS_USED
+#if defined(STM32_USART3_IS_USED)
   nvicDisableVector(STM32_USART3_NUMBER);
 #endif
 }
@@ -89,7 +76,7 @@ static inline void usart3_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_USART3_IS_USED || defined(__DOXYGEN__)
+#if defined(STM32_USART3_IS_USED) || defined(__DOXYGEN__)
 /**
  * @brief   USART3 interrupt handler.
  *
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart3_4_lp1.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart3_4_lp1.inc
index 596237fb2..a4b337f2e 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart3_4_lp1.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart3_4_lp1.inc
@@ -56,37 +56,6 @@
 
 #endif /* STM32_HAS_USART3 || STM32_HAS_UART4 || STM32_HAS_LPUART1 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_USART3) &&                          \
-    (HAL_USE_UART && STM32_UART_USE_USART3)
-#error "USART3 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART4) &&                           \
-    (HAL_USE_UART && STM32_UART_USE_UART4)
-#error "USART4 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_USART3) ||                          \
-    (HAL_USE_UART && STM32_UART_USE_USART3)
-#define STM32_USART3_IS_USED        TRUE
-#else
-#define STM32_USART3_IS_USED        FALSE
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART4) ||                           \
-    (HAL_USE_UART && STM32_UART_USE_UART4)
-#define STM32_USART4_IS_USED        TRUE
-#else
-#define STM32_USART4_IS_USED        FALSE
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_LPUART1)
-#define STM32_LPUART1_IS_USED       TRUE
-#else
-#define STM32_LPUART1_IS_USED       FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -100,13 +69,15 @@
 /*===========================================================================*/
 
 static inline void usart3_usart4_lpuart1_irq_init(void) {
-#if STM32_USART3_IS_USED || STM32_USART4_IS_USED || STM32_LPUART1_IS_USED
+#if defined(STM32_USART3_IS_USED) || defined(STM32_UART4_IS_USED) ||        \
+    defined(STM32_LPUART1_IS_USED)
   nvicEnableVector(STM32_USART3_4_LP1_NUMBER, STM32_IRQ_USART3_4_LP1_PRIORITY);
 #endif
 }
 
 static inline void usart3_usart4_lpuart1_irq_deinit(void) {
-#if STM32_USART3_IS_USED || STM32_USART4_IS_USED || STM32_LPUART1_IS_USED
+#if defined(STM32_USART3_IS_USED) || defined(STM32_UART4_IS_USED) ||        \
+    defined(STM32_LPUART1_IS_USED)
   nvicDisableVector(STM32_USART3_4_LP1_NUMBER);
 #endif
 }
@@ -115,8 +86,8 @@ static inline void usart3_usart4_lpuart1_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_USART3_IS_USED  || STM32_USART4_IS_USED ||                         \
-    STM32_LPUART1_IS_USED || defined(__DOXYGEN__)
+#if defined(STM32_USART3_IS_USED)  || defined(STM32_UART4_IS_USED) ||       \
+    defined(STM32_LPUART1_IS_USED) || defined(__DOXYGEN__)
 /**
  * @brief   USART4, USART5, LPUART1 interrupt handler.
  *
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart4_5.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart4_5.inc
index 7d003a3c6..89edaedb1 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart4_5.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart4_5.inc
@@ -52,31 +52,6 @@
 
 #endif /* STM32_HAS_UART4 || STM32_HAS_UART5 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART4) &&                           \
-    (HAL_USE_UART && STM32_UART_USE_UART4)
-#error "USART4 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART5) &&                           \
-    (HAL_USE_UART && STM32_UART_USE_UART5)
-#error "USART5 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART4) ||                           \
-    (HAL_USE_UART && STM32_UART_USE_UART4)
-#define STM32_USART4_IS_USED        TRUE
-#else
-#define STM32_USART4_IS_USED        FALSE
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_UART5) ||                           \
-    (HAL_USE_UART && STM32_UART_USE_UART45)
-#define STM32_USART5_IS_USED        TRUE
-#else
-#define STM32_USART5_IS_USED        FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -90,13 +65,13 @@
 /*===========================================================================*/
 
 static inline void usart4_usart5_irq_init(void) {
-#if STM32_USART4_IS_USED || STM32_USART5_IS_USED
+#if defined(STM32_UART4_IS_USED) || defined(STM32_UART5_IS_USED)
   nvicEnableVector(STM32_USART4_5_NUMBER, STM32_IRQ_USART4_5_PRIORITY);
 #endif
 }
 
 static inline void usart4_usart5_irq_deinit(void) {
-#if STM32_USART4_IS_USED || STM32_USART5_IS_USED
+#if defined(STM32_UART4_IS_USED) || defined(STM32_UART5_IS_USED)
   nvicDisableVector(STM32_USART4_5_NUMBER);
 #endif
 }
@@ -105,7 +80,7 @@ static inline void usart4_usart5_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_USART4_IS_USED  || STM32_USART5_IS_USED ||                        \
+#if defined(STM32_UART4_IS_USED)  || defined(STM32_UART5_IS_USED) ||        \
     defined(__DOXYGEN__)
 /**
  * @brief   USART4, USART5, LPUART1 interrupt handler.
diff --git a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart6.inc b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart6.inc
index ea812a8e9..fd09e7c10 100644
--- a/os/hal/ports/STM32/LLD/USARTv2/stm32_usart6.inc
+++ b/os/hal/ports/STM32/LLD/USARTv2/stm32_usart6.inc
@@ -48,19 +48,6 @@
 
 #endif /* STM32_HAS_USART6 */
 
-/* Other checks.*/
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_USART6) &&                          \
-    (HAL_USE_UART && STM32_UART_USE_USART6)
-#error "USART6 used by multiple drivers"
-#endif
-
-#if (HAL_USE_SERIAL && STM32_SERIAL_USE_USART6) ||                          \
-    (HAL_USE_UART && STM32_UART_USE_USART6)
-#define STM32_USART6_IS_USED        TRUE
-#else
-#define STM32_USART6_IS_USED        FALSE
-#endif
-
 /*===========================================================================*/
 /* Driver exported variables.                                                */
 /*===========================================================================*/
@@ -74,13 +61,13 @@
 /*===========================================================================*/
 
 static inline void usart6_irq_init(void) {
-#if STM32_USART6_IS_USED
+#if defined(STM32_USART6_IS_USED)
   nvicEnableVector(STM32_USART6_NUMBER, STM32_IRQ_USART6_PRIORITY);
 #endif
 }
 
 static inline void usart6_irq_deinit(void) {
-#if STM32_USART6_IS_USED
+#if defined(STM32_USART6_IS_USED)
   nvicDisableVector(STM32_USART6_NUMBER);
 #endif
 }
@@ -89,7 +76,7 @@ static inline void usart6_irq_deinit(void) {
 /* Driver interrupt handlers.                                                */
 /*===========================================================================*/
 
-#if STM32_USART6_IS_USED || defined(__DOXYGEN__)
+#if defined(STM32_USART6_IS_USED) || defined(__DOXYGEN__)
 /**
  * @brief   USART6 interrupt handler.
  *
diff --git a/readme.txt b/readme.txt
index f95e32ace..477f0ea3a 100644
--- a/readme.txt
+++ b/readme.txt
@@ -74,6 +74,8 @@
 *****************************************************************************
 
 *** Next ***
+- NEW: Simplified USART units use collision detection in STM32 HAL, now it is
+       done like for TIM units for consistency.
 - NEW: Identification macros such as__CHIBIOS_RT__ are now prefixed by
        two underscores.
 - NEW: Support for 3 analog watchdogs in ADCv3 (STM32F3, L4, L4+, G4).