diff --git a/libraries/mbed/targets/hal/TARGET_STM/TARGET_NUCLEO_L152RE/pinmap.c b/libraries/mbed/targets/hal/TARGET_STM/TARGET_NUCLEO_L152RE/pinmap.c
index 171c93d733..3035855ede 100644
--- a/libraries/mbed/targets/hal/TARGET_STM/TARGET_NUCLEO_L152RE/pinmap.c
+++ b/libraries/mbed/targets/hal/TARGET_STM/TARGET_NUCLEO_L152RE/pinmap.c
@@ -108,7 +108,8 @@ void pin_mode(PinName pin, PinMode mode) {
   
     if (pin == NC) return;
   
-    uint32_t pin_number = (uint32_t)pin;   
+    uint32_t pin_number = (uint32_t)pin;
+    uint32_t pin_index  = (pin_number & 0xF);
     uint32_t port_index = (pin_number >> 4);
 
     // Get GPIO structure base address and enable clock  
@@ -141,7 +142,7 @@ void pin_mode(PinName pin, PinMode mode) {
     // Configure pull-up/pull-down resistors
     uint32_t pupd = (uint32_t)mode;
     if (pupd > 2) pupd = 0; // Open-drain = No pull-up/No pull-down
-    gpio->PUPDR &= (uint32_t)(~(GPIO_PUPDR_PUPDR0 << (pin_number * 2)));
-    gpio->PUPDR |= (uint32_t)(pupd << (pin_number * 2));
+    gpio->PUPDR &= (uint32_t)(~(GPIO_PUPDR_PUPDR0 << (pin_index * 2)));
+    gpio->PUPDR |= (uint32_t)(pupd << (pin_index * 2));
     
 }