diff --git a/drivers/hwspinlock/stm32_hwspinlock.c b/drivers/hwspinlock/stm32_hwspinlock.c
index 5bd11a7fab65..bb5c7e5f7a80 100644
--- a/drivers/hwspinlock/stm32_hwspinlock.c
+++ b/drivers/hwspinlock/stm32_hwspinlock.c
@@ -73,15 +73,13 @@ static int stm32_hwspinlock_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	struct stm32_hwspinlock *hw;
 	void __iomem *io_base;
-	size_t array_size;
 	int i, ret;
 
 	io_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(io_base))
 		return PTR_ERR(io_base);
 
-	array_size = STM32_MUTEX_NUM_LOCKS * sizeof(struct hwspinlock);
-	hw = devm_kzalloc(dev, sizeof(*hw) + array_size, GFP_KERNEL);
+	hw = devm_kzalloc(dev, struct_size(hw, bank.lock, STM32_MUTEX_NUM_LOCKS), GFP_KERNEL);
 	if (!hw)
 		return -ENOMEM;