diff --git a/stm-firmware/stm-periph/spi.c b/stm-firmware/stm-periph/spi.c
index 881004e..53f0acf 100644
--- a/stm-firmware/stm-periph/spi.c
+++ b/stm-firmware/stm-periph/spi.c
@@ -104,6 +104,7 @@ stm_spi_handle spi_init(struct stm_spi_dev *spi_dev_struct, SPI_TypeDef *spi_reg
 	ret_handle = spi_dev_struct;
 
 	spi_dev_struct->settings.cs_deactivate();
+	spi_dev_struct->magic = STM_SPI_DEV_MAGIC;
 
 exit:
 	return ret_handle;
@@ -118,6 +119,8 @@ void spi_deinit(stm_spi_handle handle)
 	if (!dev)
 		return;
 
+	dev->magic = 0UL;
+
 	dev->spi_regs->CR1 = 0;
 	dev->spi_regs->CR2 = 0;