diff --git a/targets/TARGET_STM/TARGET_STM32F0/pinmap.c b/targets/TARGET_STM/TARGET_STM32F0/pinmap.c
index 791b8736bd..414fe83fba 100644
--- a/targets/TARGET_STM/TARGET_STM32F0/pinmap.c
+++ b/targets/TARGET_STM/TARGET_STM32F0/pinmap.c
@@ -49,42 +49,7 @@ static const uint32_t gpio_mode[13] = {
     0x10000000  // 12 = Reset IT and EVT (not in STM32Cube HAL)
 };
 
-// Enable GPIO clock and return GPIO base address
-uint32_t Set_GPIO_Clock(uint32_t port_idx) {
-    uint32_t gpio_add = 0;
-    switch (port_idx) {
-        case PortA:
-            gpio_add = GPIOA_BASE;
-            __GPIOA_CLK_ENABLE();
-            break;
-        case PortB:
-            gpio_add = GPIOB_BASE;
-            __GPIOB_CLK_ENABLE();
-            break;
-#if defined(GPIOC_BASE)
-        case PortC:
-            gpio_add = GPIOC_BASE;
-            __GPIOC_CLK_ENABLE();
-            break;
-#endif
-#if defined(GPIOD_BASE)
-        case PortD:
-            gpio_add = GPIOD_BASE;
-            __GPIOD_CLK_ENABLE();
-            break;
-#endif
-#if defined(GPIOF_BASE)
-        case PortF:
-            gpio_add = GPIOF_BASE;
-            __GPIOF_CLK_ENABLE();
-            break;
-#endif
-        default:
-            error("Pinmap error: wrong port number.");
-            break;
-    }
-    return gpio_add;
-}
+extern GPIO_TypeDef *Set_GPIO_Clock(uint32_t port_idx);
 
 /**
  * Configure pin (mode, speed, output type and pull-up/pull-down)
@@ -101,8 +66,7 @@ void pin_function(PinName pin, int data) {
     uint32_t pin_index  = STM_PIN(pin);
 
     // Enable GPIO clock
-    uint32_t gpio_add = Set_GPIO_Clock(port_index);
-    GPIO_TypeDef *gpio = (GPIO_TypeDef *)gpio_add;
+    GPIO_TypeDef *gpio = Set_GPIO_Clock(port_index);
 
     // Configure GPIO
     GPIO_InitTypeDef GPIO_InitStructure;
@@ -130,8 +94,7 @@ void pin_mode(PinName pin, PinMode mode) {
     uint32_t pin_index  = STM_PIN(pin);
 
     // Enable GPIO clock
-    uint32_t gpio_add = Set_GPIO_Clock(port_index);
-    GPIO_TypeDef *gpio = (GPIO_TypeDef *)gpio_add;
+    GPIO_TypeDef *gpio = Set_GPIO_Clock(port_index);
 
     // Configure pull-up/pull-down resistors
     uint32_t pupd = (uint32_t)mode;
@@ -148,7 +111,7 @@ void pin_function_gpiomode(PinName pin, uint32_t gpiomode) {
     /* Read current pull state from HW to avoid over-write*/
     uint32_t port_index = STM_PORT(pin);
     uint32_t pin_index  = STM_PIN(pin);
-    GPIO_TypeDef *gpio = (GPIO_TypeDef *) Set_GPIO_Clock(port_index);
+    GPIO_TypeDef *gpio = Set_GPIO_Clock(port_index);
     uint32_t temp = gpio->PUPDR;
     uint32_t pull = (temp  >> (pin_index * 2U)) & GPIO_PUPDR_PUPDR0;
 
diff --git a/targets/TARGET_STM/gpio_api.c b/targets/TARGET_STM/gpio_api.c
index 560350f13e..477043d1b3 100644
--- a/targets/TARGET_STM/gpio_api.c
+++ b/targets/TARGET_STM/gpio_api.c
@@ -32,7 +32,78 @@
 #include "pinmap.h"
 #include "mbed_error.h"
 
-extern uint32_t Set_GPIO_Clock(uint32_t port_idx);
+// Enable GPIO clock and return GPIO base address
+GPIO_TypeDef *Set_GPIO_Clock(uint32_t port_idx) {
+    uint32_t gpio_add = 0;
+    switch (port_idx) {
+        case PortA:
+            gpio_add = GPIOA_BASE;
+            __GPIOA_CLK_ENABLE();
+            break;
+        case PortB:
+            gpio_add = GPIOB_BASE;
+            __GPIOB_CLK_ENABLE();
+            break;
+#if defined(GPIOC_BASE)
+        case PortC:
+            gpio_add = GPIOC_BASE;
+            __GPIOC_CLK_ENABLE();
+            break;
+#endif
+#if defined GPIOD_BASE
+        case PortD:
+            gpio_add = GPIOD_BASE;
+            __GPIOD_CLK_ENABLE();
+            break;
+#endif
+#if defined GPIOE_BASE
+        case PortE:
+            gpio_add = GPIOE_BASE;
+            __GPIOE_CLK_ENABLE();
+            break;
+#endif
+#if defined GPIOF_BASE
+        case PortF:
+            gpio_add = GPIOF_BASE;
+            __GPIOF_CLK_ENABLE();
+            break;
+#endif
+#if defined GPIOG_BASE
+        case PortG:
+            gpio_add = GPIOG_BASE;
+            __GPIOG_CLK_ENABLE();
+            break;
+#endif
+#if defined GPIOH_BASE
+        case PortH:
+            gpio_add = GPIOH_BASE;
+            __GPIOH_CLK_ENABLE();
+            break;
+#endif
+#if defined GPIOI_BASE
+        case PortI:
+            gpio_add = GPIOI_BASE;
+            __GPIOI_CLK_ENABLE();
+            break;
+#endif
+#if defined GPIOJ_BASE
+        case PortJ:
+            gpio_add = GPIOJ_BASE;
+            __GPIOJ_CLK_ENABLE();
+            break;
+#endif
+#if defined GPIOK_BASE
+        case PortK:
+            gpio_add = GPIOK_BASE;
+            __GPIOK_CLK_ENABLE();
+            break;
+#endif
+        default:
+            error("Pinmap error: wrong port number.");
+            break;
+    }
+    return (GPIO_TypeDef *) gpio_add;
+}
 
 uint32_t gpio_set(PinName pin) {
     MBED_ASSERT(pin != (PinName)NC);
@@ -51,8 +122,7 @@ void gpio_init(gpio_t *obj, PinName pin) {
     uint32_t port_index = STM_PORT(pin);
 
     // Enable GPIO clock
-    uint32_t gpio_add = Set_GPIO_Clock(port_index);
-    GPIO_TypeDef *gpio = (GPIO_TypeDef *)gpio_add;
+    GPIO_TypeDef *gpio = Set_GPIO_Clock(port_index);
 
     // Fill GPIO object structure for future use
     obj->mask    = gpio_set(pin);
diff --git a/targets/TARGET_STM/gpio_irq_api.c b/targets/TARGET_STM/gpio_irq_api.c
index 2c78b599f1..9af8f901e0 100644
--- a/targets/TARGET_STM/gpio_irq_api.c
+++ b/targets/TARGET_STM/gpio_irq_api.c
@@ -43,7 +43,7 @@
 typedef struct gpio_channel {
     uint32_t pin_mask;                   // bitmask representing which pins are configured for receiving interrupts
     uint32_t channel_ids[MAX_PIN_LINE];  // mbed "gpio_irq_t gpio_irq" field of instance
-    uint32_t channel_gpio[MAX_PIN_LINE]; // base address of gpio port group
+    GPIO_TypeDef* channel_gpio[MAX_PIN_LINE]; // base address of gpio port group
     uint32_t channel_pin[MAX_PIN_LINE];  // pin number in port group
 } gpio_channel_t;
 
@@ -159,7 +159,7 @@ static void gpio_irq6(void)
 }
 #endif
 
-extern uint32_t Set_GPIO_Clock(uint32_t port_idx);
+extern GPIO_TypeDef *Set_GPIO_Clock(uint32_t port_idx);
 extern void pin_function_gpiomode(PinName pin, uint32_t gpiomode);
 
 int gpio_irq_init(gpio_irq_t *obj, PinName pin, gpio_irq_handler handler, uint32_t id)
@@ -221,7 +221,7 @@ int gpio_irq_init(gpio_irq_t *obj, PinName pin, gpio_irq_handler handler, uint32
     }
 
     // Enable GPIO clock
-    uint32_t gpio_add = Set_GPIO_Clock(port_index);
+    GPIO_TypeDef *gpio_add = Set_GPIO_Clock(port_index);
 
     // Save informations for future use
     obj->irq_n = pin_lines_desc[pin_index].irq_n;
diff --git a/targets/TARGET_STM/port_api.c b/targets/TARGET_STM/port_api.c
index 532b57e8fa..04c7c8a280 100644
--- a/targets/TARGET_STM/port_api.c
+++ b/targets/TARGET_STM/port_api.c
@@ -34,7 +34,7 @@
 
 #if DEVICE_PORTIN || DEVICE_PORTOUT
 
-extern uint32_t Set_GPIO_Clock(uint32_t port_idx);
+extern GPIO_TypeDef *Set_GPIO_Clock(uint32_t port_idx);
 
 // high nibble = port number (0=A, 1=B, 2=C, 3=D, 4=E, 5=F, ...)
 // low nibble  = pin number
@@ -48,8 +48,7 @@ void port_init(port_t *obj, PortName port, int mask, PinDirection dir)
     uint32_t port_index = (uint32_t)port;
 
     // Enable GPIO clock
-    uint32_t gpio_add = Set_GPIO_Clock(port_index);
-    GPIO_TypeDef *gpio = (GPIO_TypeDef *)gpio_add;
+    GPIO_TypeDef *gpio =  Set_GPIO_Clock(port_index);
 
     // Fill PORT object structure for future use
     obj->port      = port;