diff --git a/os/hal/ports/STM32/STM32F0xx/hal_lld.c b/os/hal/ports/STM32/STM32F0xx/hal_lld.c
index f97e3fbb1..c472e11e9 100644
--- a/os/hal/ports/STM32/STM32F0xx/hal_lld.c
+++ b/os/hal/ports/STM32/STM32F0xx/hal_lld.c
@@ -32,6 +32,12 @@
 /* Driver exported variables.                                                */
 /*===========================================================================*/
 
+/**
+ * @brief   CMSIS system core clock variable.
+ * @note    It is declared in system_stm32f0xx.h.
+ */
+uint32_t SystemCoreClock = STM32_SYSCLK;
+
 /*===========================================================================*/
 /* Driver local variables and types.                                         */
 /*===========================================================================*/
diff --git a/os/hal/ports/STM32/STM32F1xx/hal_lld.c b/os/hal/ports/STM32/STM32F1xx/hal_lld.c
index 0aac5ffff..989ab35a7 100644
--- a/os/hal/ports/STM32/STM32F1xx/hal_lld.c
+++ b/os/hal/ports/STM32/STM32F1xx/hal_lld.c
@@ -32,6 +32,12 @@
 /* Driver exported variables.                                                */
 /*===========================================================================*/
 
+/**
+ * @brief   CMSIS system core clock variable.
+ * @note    It is declared in system_stm32f10x.h.
+ */
+uint32_t SystemCoreClock = STM32_SYSCLK;
+
 /*===========================================================================*/
 /* Driver local variables and types.                                         */
 /*===========================================================================*/
diff --git a/os/hal/ports/STM32/STM32F37x/hal_lld.c b/os/hal/ports/STM32/STM32F37x/hal_lld.c
index e21674463..411c420ea 100644
--- a/os/hal/ports/STM32/STM32F37x/hal_lld.c
+++ b/os/hal/ports/STM32/STM32F37x/hal_lld.c
@@ -32,6 +32,12 @@
 /* Driver exported variables.                                                */
 /*===========================================================================*/
 
+/**
+ * @brief   CMSIS system core clock variable.
+ * @note    It is declared in system_stm32f3xx.h.
+ */
+uint32_t SystemCoreClock = STM32_SYSCLK;
+
 /*===========================================================================*/
 /* Driver local variables and types.                                         */
 /*===========================================================================*/
diff --git a/os/hal/ports/STM32/STM32F3xx/hal_lld.c b/os/hal/ports/STM32/STM32F3xx/hal_lld.c
index 5fe983e79..874ba8ef5 100644
--- a/os/hal/ports/STM32/STM32F3xx/hal_lld.c
+++ b/os/hal/ports/STM32/STM32F3xx/hal_lld.c
@@ -32,6 +32,12 @@
 /* Driver exported variables.                                                */
 /*===========================================================================*/
 
+/**
+ * @brief   CMSIS system core clock variable.
+ * @note    It is declared in system_stm32f3xx.h.
+ */
+uint32_t SystemCoreClock = STM32_SYSCLK;
+
 /*===========================================================================*/
 /* Driver local variables and types.                                         */
 /*===========================================================================*/
diff --git a/os/hal/ports/STM32/STM32F4xx/hal_lld.c b/os/hal/ports/STM32/STM32F4xx/hal_lld.c
index da9e1aa4c..4bb3f4fcd 100644
--- a/os/hal/ports/STM32/STM32F4xx/hal_lld.c
+++ b/os/hal/ports/STM32/STM32F4xx/hal_lld.c
@@ -32,6 +32,12 @@
 /* Driver exported variables.                                                */
 /*===========================================================================*/
 
+/**
+ * @brief   CMSIS system core clock variable.
+ * @note    It is declared in system_stm32f4xx.h.
+ */
+uint32_t SystemCoreClock = STM32_SYSCLK;
+
 /*===========================================================================*/
 /* Driver local variables and types.                                         */
 /*===========================================================================*/
diff --git a/os/hal/ports/STM32/STM32L1xx/hal_lld.c b/os/hal/ports/STM32/STM32L1xx/hal_lld.c
index 749e33a7f..0be1fa067 100644
--- a/os/hal/ports/STM32/STM32L1xx/hal_lld.c
+++ b/os/hal/ports/STM32/STM32L1xx/hal_lld.c
@@ -34,6 +34,12 @@
 /* Driver exported variables.                                                */
 /*===========================================================================*/
 
+/**
+ * @brief   CMSIS system core clock variable.
+ * @note    It is declared in system_stm32l1xx.h.
+ */
+uint32_t SystemCoreClock = STM32_SYSCLK;
+
 /*===========================================================================*/
 /* Driver local variables and types.                                         */
 /*===========================================================================*/