diff --git a/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32F4/i2c_api.c b/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32F4/i2c_api.c
index 868ffd3d12..7ded748f4d 100644
--- a/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32F4/i2c_api.c
+++ b/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32F4/i2c_api.c
@@ -100,7 +100,7 @@ void i2c_init(i2c_t *obj, PinName sda, PinName scl)
 
 void i2c_frequency(i2c_t *obj, int hz)
 {
-    MBED_ASSERT((hz != 0) && (hz <= 400000));
+    MBED_ASSERT((hz > 0) && (hz <= 400000));
     I2cHandle.Instance = (I2C_TypeDef *)(obj->i2c);
     int timeout;
 
@@ -135,8 +135,8 @@ inline int i2c_start(i2c_t *obj)
     // Clear Acknowledge failure flag
     __HAL_I2C_CLEAR_FLAG(&I2cHandle, I2C_FLAG_AF);
 
-    // Generate the START condition
-    i2c->CR1 |= I2C_CR1_START;
+    // Generate the START condition and remove an eventual pending STOP bit
+    i2c->CR1 = ((i2c->CR1 & ~I2C_CR1_STOP) | I2C_CR1_START);
 
     // Wait the START condition has been correctly sent
     timeout = FLAG_TIMEOUT;