diff --git a/include/arm11/hardware/i2c.h b/include/arm11/hardware/i2c.h
index a9c298b..5e1e104 100644
--- a/include/arm11/hardware/i2c.h
+++ b/include/arm11/hardware/i2c.h
@@ -97,3 +97,14 @@
  * @return     Returns true on success and false on failure.
  */
 bool I2C_writeReg(I2cDevice devId, u8 regAddr, u8 data);
+
+/**
+ * @brief      Writes a byte to a I2C register without interrupts.
+ *
+ * @param[in]  devId    The device ID. Use the enum above.
+ * @param[in]  regAddr  The register address.
+ * @param[in]  data     The data to write.
+ *
+ * @return     Returns true on success and false on failure.
+ */
+bool I2C_writeRegIntSafe(I2cDevice devId, u8 regAddr, u8 data);
diff --git a/source/arm11/hardware/i2c.c b/source/arm11/hardware/i2c.c
index ac816e5..0274dda 100644
--- a/source/arm11/hardware/i2c.c
+++ b/source/arm11/hardware/i2c.c
@@ -242,3 +242,52 @@
 {
 	return I2C_writeRegBuf(devId, regAddr, &data, 1);
 }
+
+bool I2C_writeRegIntSafe(I2cDevice devId, u8 regAddr, u8 data)
+{
+	const u8 busId = i2cDevTable[devId].busId;
+	const u8 devAddr = i2cDevTable[devId].devAddr;
+	I2cRegs *const regs = i2cGetBusRegsBase(busId);
+
+
+	u32 tries = 8;
+	do
+	{
+		while(regs->I2C_CNT & I2C_ENABLE);
+
+		// Select device and start.
+		regs->I2C_DATA = devAddr;
+		regs->I2C_CNT = I2C_ENABLE | I2C_DIRE_WRITE | I2C_START;
+		while(regs->I2C_CNT & I2C_ENABLE);
+		if(!(regs->I2C_CNT & I2C_ACK)) // If ack flag is 0 it failed.
+		{
+			regs->I2C_CNT = I2C_ENABLE | I2C_ERROR | I2C_STOP;
+			continue;
+		}
+
+		// Select register.
+		regs->I2C_DATA = regAddr;
+		regs->I2C_CNT = I2C_ENABLE | I2C_DIRE_WRITE;
+		while(regs->I2C_CNT & I2C_ENABLE);
+		if(!(regs->I2C_CNT & I2C_ACK))
+		{
+			regs->I2C_CNT = I2C_ENABLE | I2C_ERROR | I2C_STOP;
+			continue;
+		}
+
+		break;
+	} while(--tries > 0);
+
+	if(tries == 0) return false;
+
+	regs->I2C_DATA = data;
+	regs->I2C_CNT = I2C_ENABLE | I2C_DIRE_WRITE | I2C_STOP;
+	while(regs->I2C_CNT & I2C_ENABLE);
+	if(!(regs->I2C_CNT & I2C_ACK))
+	{
+		regs->I2C_CNT = I2C_ENABLE | I2C_ERROR | I2C_STOP;
+		return false;
+	}
+
+	return true;
+}
diff --git a/source/arm11/hardware/mcu.c b/source/arm11/hardware/mcu.c
index c1b5093..7c1dd6c 100644
--- a/source/arm11/hardware/mcu.c
+++ b/source/arm11/hardware/mcu.c
@@ -70,12 +70,12 @@
 
 void MCU_triggerPowerOff(void)
 {
-	I2C_writeReg(I2C_DEV_MCU, RegPower, 1);
+	I2C_writeRegIntSafe(I2C_DEV_MCU, RegPower, 1);
 }
 
 void MCU_triggerReboot(void)
 {
-	I2C_writeReg(I2C_DEV_MCU, RegPower, 1u << 2);
+	I2C_writeRegIntSafe(I2C_DEV_MCU, RegPower, 1u << 2);
 }
 
 u8 MCU_readBatteryLevel(void)