diff --git a/targets/TARGET_STM/can_api.c b/targets/TARGET_STM/can_api.c
index 4ee8b9e99d..163597c261 100644
--- a/targets/TARGET_STM/can_api.c
+++ b/targets/TARGET_STM/can_api.c
@@ -100,12 +100,8 @@ static void _can_init_freq_direct(can_t *obj, const can_pinmap_t *pinmap, int hz
     pin_function(pinmap->rd_pin, pinmap->rd_function);
     pin_function(pinmap->td_pin, pinmap->td_function);
     // Add pull-ups
-    if (pinmap->rd_pin != NC) {
-        pin_mode(pinmap->rd_pin, PullUp);
-    }
-    if (pinmap->td_pin != NC) {
-        pin_mode(pinmap->td_pin, PullUp);
-    }
+    pin_mode(pinmap->rd_pin, PullUp);
+    pin_mode(pinmap->td_pin, PullUp);
 
     // Default values
     obj->CanHandle.Instance = (FDCAN_GlobalTypeDef *)pinmap->peripheral;
@@ -599,12 +595,8 @@ static void _can_init_freq_direct(can_t *obj, const can_pinmap_t *pinmap, int hz
     pin_function(pinmap->rd_pin, pinmap->rd_function);
     pin_function(pinmap->td_pin, pinmap->td_function);
     // Add pull-ups
-    if (pinmap->rd_pin != NC) {
-        pin_mode(pinmap->rd_pin, PullUp);
-    }
-    if (pinmap->td_pin != NC) {
-        pin_mode(pinmap->td_pin, PullUp);
-    }
+    pin_mode(pinmap->rd_pin, PullUp);
+    pin_mode(pinmap->td_pin, PullUp);
 
     /*  Use default values for rist init */
     obj->CanHandle.Instance = (CAN_TypeDef *)pinmap->peripheral;
diff --git a/targets/TARGET_STM/pinmap.c b/targets/TARGET_STM/pinmap.c
index 467544c56e..ce761e2d47 100644
--- a/targets/TARGET_STM/pinmap.c
+++ b/targets/TARGET_STM/pinmap.c
@@ -59,7 +59,9 @@ const uint32_t ll_pin_defines[16] = {
  */
 void pin_function(PinName pin, int data)
 {
-    MBED_ASSERT(pin != (PinName)NC);
+    if (pin == NC) {
+        return;
+    }
 
     // Get the pin informations
     uint32_t mode  = STM_PIN_FUNCTION(data);
@@ -163,7 +165,9 @@ void pin_function(PinName pin, int data)
  */
 void pin_mode(PinName pin, PinMode mode)
 {
-    MBED_ASSERT(pin != (PinName)NC);
+    if (pin == NC) {
+        return;
+    }
 
     uint32_t port_index = STM_PORT(pin);
     uint32_t ll_pin  = ll_pin_defines[STM_PIN(pin)];
diff --git a/targets/TARGET_STM/serial_api.c b/targets/TARGET_STM/serial_api.c
index 4ac3f3d50d..62f6054866 100644
--- a/targets/TARGET_STM/serial_api.c
+++ b/targets/TARGET_STM/serial_api.c
@@ -157,14 +157,10 @@ static void _serial_init_direct(serial_t *obj, const serial_pinmap_t *pinmap)
     MBED_ASSERT(obj_s->index >= 0);
 
     // Configure UART pins
-    if (pinmap->tx_pin != NC) {
-        pin_function(pinmap->tx_pin, pinmap->tx_function);
-        pin_mode(pinmap->tx_pin, PullUp);
-    }
-    if (pinmap->rx_pin != NC) {
-        pin_function(pinmap->rx_pin, pinmap->rx_function);
-        pin_mode(pinmap->rx_pin, PullUp);
-    }
+    pin_function(pinmap->tx_pin, pinmap->tx_function);
+    pin_mode(pinmap->tx_pin, PullUp);
+    pin_function(pinmap->rx_pin, pinmap->rx_function);
+    pin_mode(pinmap->rx_pin, PullUp);
 
     // Configure UART
     obj_s->baudrate = 9600; // baudrate default value
@@ -355,13 +351,9 @@ void serial_free(serial_t *obj)
 #endif /* DUAL_CORE */
 
     // Configure GPIOs
-    if (obj_s->pin_tx != NC) {
-        pin_function(obj_s->pin_tx, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
-    }
+    pin_function(obj_s->pin_tx, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
 
-    if (obj_s->pin_rx != NC) {
-        pin_function(obj_s->pin_rx, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
-    }
+    pin_function(obj_s->pin_rx, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
 
     serial_irq_ids[obj_s->index] = 0;
 }
diff --git a/targets/TARGET_STM/stm_spi_api.c b/targets/TARGET_STM/stm_spi_api.c
index 9bcc0bc2a4..d6d2aaa4d0 100644
--- a/targets/TARGET_STM/stm_spi_api.c
+++ b/targets/TARGET_STM/stm_spi_api.c
@@ -218,14 +218,12 @@ static void _spi_init_direct(spi_t *obj, const spi_pinmap_t *pinmap)
 #endif
 
     // Configure the SPI pins
-    if (pinmap->mosi_pin != NC) {
-        pin_function(pinmap->mosi_pin, pinmap->mosi_function);
-        pin_mode(pinmap->mosi_pin, PullNone);
-    }
-    if (pinmap->miso_pin != NC) {
-        pin_function(pinmap->miso_pin, pinmap->miso_function);
-        pin_mode(pinmap->miso_pin, PullNone);
-    }
+    pin_function(pinmap->mosi_pin, pinmap->mosi_function);
+    pin_mode(pinmap->mosi_pin, PullNone);
+
+    pin_function(pinmap->miso_pin, pinmap->miso_function);
+    pin_mode(pinmap->miso_pin, PullNone);
+
     pin_function(pinmap->sclk_pin, pinmap->sclk_function);
     pin_mode(pinmap->sclk_pin, PullNone);
     spiobj->pin_miso = pinmap->miso_pin;
@@ -370,12 +368,8 @@ void spi_free(spi_t *obj)
     LL_HSEM_ReleaseLock(HSEM, CFG_HW_RCC_SEMID, HSEM_CR_COREID_CURRENT);
 #endif /* DUAL_CORE */
     // Configure GPIOs
-    if (spiobj->pin_miso != NC) {
-        pin_function(spiobj->pin_miso, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
-    }
-    if (spiobj->pin_mosi != NC) {
-        pin_function(spiobj->pin_mosi, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
-    }
+    pin_function(spiobj->pin_miso, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
+    pin_function(spiobj->pin_mosi, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
     pin_function(spiobj->pin_sclk, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
     if (handle->Init.NSS != SPI_NSS_SOFT) {
         pin_function(spiobj->pin_ssel, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));