diff --git a/fw/Core/Src/i2c.c b/fw/Core/Src/i2c.c
index 8d68186..8385345 100644
--- a/fw/Core/Src/i2c.c
+++ b/fw/Core/Src/i2c.c
@@ -50,6 +50,7 @@ int8_t i2c_receive(uint8_t address, uint8_t *buffer, int len)
 {
 	LL_I2C_HandleTransfer(i2c_context->i2c, address, LL_I2C_ADDRSLAVE_7BIT, len,
 				LL_I2C_MODE_AUTOEND, LL_I2C_GENERATE_START_READ);
+	LL_I2C_ClearFlag_STOP(i2c_context->i2c);
 	int i = 0;
 	while (!LL_I2C_IsActiveFlag_STOP(i2c_context->i2c)) {
 		if (LL_I2C_IsActiveFlag_RXNE(i2c_context->i2c)) {
diff --git a/fw/Core/Src/scd4x.c b/fw/Core/Src/scd4x.c
index 6452c3a..958d35c 100644
--- a/fw/Core/Src/scd4x.c
+++ b/fw/Core/Src/scd4x.c
@@ -100,7 +100,6 @@ int8_t scd4x_read_measurement(uint16_t *co2, int16_t *temperature, uint16_t *rel
 	uint8_t t_crc = buffer[5];
 	uint32_t rh_ticks = (buffer[6] << 8) + buffer[7];
 	uint8_t rh_crc = buffer[8];
-
 	/* check CRC-8 checksum */
 	uint8_t crc_correct = crc8_calculate(buffer, 2) == co2_crc;
 	crc_correct &= crc8_calculate(buffer + 3, 2) == t_crc;
diff --git a/fw/Core/Src/sht4x.c b/fw/Core/Src/sht4x.c
index 181a4bf..9033319 100644
--- a/fw/Core/Src/sht4x.c
+++ b/fw/Core/Src/sht4x.c
@@ -23,29 +23,35 @@ int8_t sht4x_measure(int16_t *temperature, uint16_t *relative_humidity)
 	uint8_t buffer[32];
 	int result;
 
-	// disable interrupts to prevent modbus/i2c conflict
+	/* disable interrupts to prevent modbus/i2c conflict */
 	uart_disable_interrupts();
 	// start measurement
 	buffer[0] = SHT4X_START_MEAS_HIGH_PRECISION;
 	result = i2c_transmit(SHT4X_I2C_ADDRESS<<1, buffer, 1);
-	// TODO: Proc to vraci NACK? Vyresit.
-	/*
 	if (result != I2C_OK) {
 		return SHT4X_ERROR;
-	}*/
+	}
 	uart_enable_interrupts();
-	LL_mDelay(10); // 10 ms should be enough
+	LL_mDelay(10); /* 10 ms should be enough */
 	uart_disable_interrupts();
-	// read out
+	/* read out */
 	result = i2c_receive(SHT4X_I2C_ADDRESS<<1, buffer, 6);
 	uart_enable_interrupts();
 	if (result != I2C_OK) {
 		return SHT4X_ERROR;
 	}
-	// TODO checksum
-	// Convert to T and RH; taken directly from pseudocode in SHT4x datasheet, page 3
+	/* Convert to T and RH; taken directly from pseudocode in SHT4x datasheet, page 3 */
 	uint32_t t_ticks = (buffer[0] << 8) + buffer[1];
+	uint8_t t_crc = buffer[2];
 	uint32_t rh_ticks = (buffer[3] << 8) + buffer[4];
+	uint8_t rh_crc = buffer[5];
+	/* check CRC-8 checksum */
+	uint8_t crc_correct = crc8_calculate(buffer, 2) == t_crc;
+	crc_correct &= crc8_calculate(buffer + 3, 2) == rh_crc;
+	if (!crc_correct) {
+		return SHT4X_CRC8_ERROR;
+	}
+	/* copy data to output variables */
 	int t_degC = -450 + 10 * 175 * t_ticks / 65535; /* temperature * 10 */
 	int rh_pRH = -6 + 125 * rh_ticks / 65535;
 	if (rh_pRH > 100) {