diff --git a/src/hal/spi.cpp b/src/hal/spi.cpp
index 0fcf150..9411bef 100644
--- a/src/hal/spi.cpp
+++ b/src/hal/spi.cpp
@@ -28,6 +28,8 @@ namespace sta
 
 	void HalSpiInterface::transfer16(uint16_t value)
 	{
+		static_assert(sizeof(uint16_t) == 2);
+
 		HAL_SPI_Transmit(handle_, reinterpret_cast<uint8_t *>(&value), 2, HAL_MAX_DELAY);
 	}
 
@@ -42,6 +44,8 @@ namespace sta
 
 	void HalSpiInterface::fill32(uint32_t value, size_t count)
 	{
+		static_assert(sizeof(uint32_t) == 4);
+
 		for (size_t i = 0; i < count; ++i)
 		{
 			HAL_SPI_Transmit(handle_, reinterpret_cast<uint8_t *>(&value), 4, HAL_MAX_DELAY);