diff --git a/hal/include/HAL/Accelerometer.hpp b/hal/include/HAL/Accelerometer.h
similarity index 100%
rename from hal/include/HAL/Accelerometer.hpp
rename to hal/include/HAL/Accelerometer.h
diff --git a/hal/include/HAL/Analog.hpp b/hal/include/HAL/Analog.h
similarity index 100%
rename from hal/include/HAL/Analog.hpp
rename to hal/include/HAL/Analog.h
diff --git a/hal/include/HAL/CAN.hpp b/hal/include/HAL/CAN.h
similarity index 100%
rename from hal/include/HAL/CAN.hpp
rename to hal/include/HAL/CAN.h
diff --git a/hal/include/HAL/Compressor.hpp b/hal/include/HAL/Compressor.h
similarity index 100%
rename from hal/include/HAL/Compressor.hpp
rename to hal/include/HAL/Compressor.h
diff --git a/hal/include/HAL/Digital.hpp b/hal/include/HAL/Digital.h
similarity index 100%
rename from hal/include/HAL/Digital.hpp
rename to hal/include/HAL/Digital.h
diff --git a/hal/include/HAL/Errors.hpp b/hal/include/HAL/Errors.h
similarity index 100%
rename from hal/include/HAL/Errors.hpp
rename to hal/include/HAL/Errors.h
diff --git a/hal/include/HAL/HAL.hpp b/hal/include/HAL/HAL.h
similarity index 95%
rename from hal/include/HAL/HAL.hpp
rename to hal/include/HAL/HAL.h
index f8c6694618..4de94aae89 100644
--- a/hal/include/HAL/HAL.hpp
+++ b/hal/include/HAL/HAL.h
@@ -8,21 +8,21 @@
 #include <stdint.h>
 #include <cmath>
 
-#include "Accelerometer.hpp"
-#include "Analog.hpp"
-#include "Compressor.hpp"
-#include "Digital.hpp"
-#include "Errors.hpp"
-#include "Interrupts.hpp"
-#include "Notifier.hpp"
-#include "PDP.hpp"
-#include "Power.hpp"
-#include "SerialPort.hpp"
-#include "Solenoid.hpp"
+#include "Accelerometer.h"
+#include "Analog.h"
+#include "Compressor.h"
+#include "Digital.h"
+#include "Errors.h"
+#include "Interrupts.h"
+#include "Notifier.h"
+#include "PDP.h"
+#include "Power.h"
+#include "SerialPort.h"
+#include "Solenoid.h"
 
-#include "Semaphore.hpp"
-#include "Task.hpp"
-#include "Utilities.hpp"
+#include "Semaphore.h"
+#include "Task.h"
+#include "Utilities.h"
 
 #define HAL_IO_CONFIG_DATA_SIZE 32
 #define HAL_SYS_STATUS_DATA_SIZE 44
diff --git a/hal/include/HAL/Interrupts.hpp b/hal/include/HAL/Interrupts.h
similarity index 100%
rename from hal/include/HAL/Interrupts.hpp
rename to hal/include/HAL/Interrupts.h
diff --git a/hal/include/HAL/Notifier.hpp b/hal/include/HAL/Notifier.h
similarity index 100%
rename from hal/include/HAL/Notifier.hpp
rename to hal/include/HAL/Notifier.h
diff --git a/hal/include/HAL/PDP.hpp b/hal/include/HAL/PDP.h
similarity index 100%
rename from hal/include/HAL/PDP.hpp
rename to hal/include/HAL/PDP.h
diff --git a/hal/include/HAL/Power.hpp b/hal/include/HAL/Power.h
similarity index 100%
rename from hal/include/HAL/Power.hpp
rename to hal/include/HAL/Power.h
diff --git a/hal/include/HAL/Semaphore.hpp b/hal/include/HAL/Semaphore.h
similarity index 100%
rename from hal/include/HAL/Semaphore.hpp
rename to hal/include/HAL/Semaphore.h
diff --git a/hal/include/HAL/SerialPort.hpp b/hal/include/HAL/SerialPort.h
similarity index 100%
rename from hal/include/HAL/SerialPort.hpp
rename to hal/include/HAL/SerialPort.h
diff --git a/hal/include/HAL/Solenoid.hpp b/hal/include/HAL/Solenoid.h
similarity index 100%
rename from hal/include/HAL/Solenoid.hpp
rename to hal/include/HAL/Solenoid.h
diff --git a/hal/include/HAL/Task.hpp b/hal/include/HAL/Task.h
similarity index 100%
rename from hal/include/HAL/Task.hpp
rename to hal/include/HAL/Task.h
diff --git a/hal/include/HAL/Utilities.hpp b/hal/include/HAL/Utilities.h
similarity index 100%
rename from hal/include/HAL/Utilities.hpp
rename to hal/include/HAL/Utilities.h
diff --git a/hal/include/HAL/cpp/Resource.hpp b/hal/include/HAL/cpp/Resource.h
similarity index 98%
rename from hal/include/HAL/cpp/Resource.hpp
rename to hal/include/HAL/cpp/Resource.h
index 502cb13814..1a7af69faf 100644
--- a/hal/include/HAL/cpp/Resource.hpp
+++ b/hal/include/HAL/cpp/Resource.h
@@ -7,7 +7,7 @@
 #pragma once
 
 #include <stdint.h>
-#include "../Errors.hpp"
+#include "../Errors.h"
 #include "HAL/cpp/priority_mutex.h"
 
 #include <vector>
diff --git a/hal/include/HAL/cpp/Semaphore.hpp b/hal/include/HAL/cpp/Semaphore.h
similarity index 100%
rename from hal/include/HAL/cpp/Semaphore.hpp
rename to hal/include/HAL/cpp/Semaphore.h
diff --git a/hal/include/Log.hpp b/hal/include/Log.h
similarity index 100%
rename from hal/include/Log.hpp
rename to hal/include/Log.h
diff --git a/hal/lib/athena/Accelerometer.cpp b/hal/lib/athena/Accelerometer.cpp
index bd0f203c55..d2b5e898f1 100644
--- a/hal/lib/athena/Accelerometer.cpp
+++ b/hal/lib/athena/Accelerometer.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Accelerometer.hpp"
+#include "HAL/Accelerometer.h"
 
 #include <assert.h>
 #include <stdint.h>
diff --git a/hal/lib/athena/Analog.cpp b/hal/lib/athena/Analog.cpp
index 2bf9d7846c..1e56f536b1 100644
--- a/hal/lib/athena/Analog.cpp
+++ b/hal/lib/athena/Analog.cpp
@@ -5,14 +5,14 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Analog.hpp"
+#include "HAL/Analog.h"
 
 #include "ChipObject.h"
 #include "FRC_NetworkCommunication/AICalibration.h"
 #include "FRC_NetworkCommunication/LoadOut.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "HAL/Port.h"
-#include "HAL/cpp/Resource.hpp"
+#include "HAL/cpp/Resource.h"
 #include "HAL/cpp/priority_mutex.h"
 
 static const long kTimebase = 40000000;  ///< 40 MHz clock
diff --git a/hal/lib/athena/Compressor.cpp b/hal/lib/athena/Compressor.cpp
index 465a409f8b..e462a317cb 100644
--- a/hal/lib/athena/Compressor.cpp
+++ b/hal/lib/athena/Compressor.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Compressor.hpp"
+#include "HAL/Compressor.h"
 #include <iostream>
 #include "ctre/PCM.h"
 
diff --git a/hal/lib/athena/Digital.cpp b/hal/lib/athena/Digital.cpp
index ce9c13f8d8..33f1793b2f 100644
--- a/hal/lib/athena/Digital.cpp
+++ b/hal/lib/athena/Digital.cpp
@@ -5,16 +5,16 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Digital.hpp"
+#include "HAL/Digital.h"
 
 #include <math.h>
 #include <stdio.h>
 #include <mutex>
 #include "ChipObject.h"
 #include "FRC_NetworkCommunication/LoadOut.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "HAL/Port.h"
-#include "HAL/cpp/Resource.hpp"
+#include "HAL/cpp/Resource.h"
 #include "HAL/cpp/priority_mutex.h"
 #include "i2clib/i2c-lib.h"
 #include "spilib/spi-lib.h"
diff --git a/hal/lib/athena/HALAthena.cpp b/hal/lib/athena/HALAthena.cpp
index 27f57430fd..bcd289c627 100644
--- a/hal/lib/athena/HALAthena.cpp
+++ b/hal/lib/athena/HALAthena.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 
 #include <signal.h>  // linux for kill
 #include <sys/prctl.h>
@@ -19,7 +19,7 @@
 #include "FRC_NetworkCommunication/FRCComm.h"
 #include "FRC_NetworkCommunication/LoadOut.h"
 #include "FRC_NetworkCommunication/UsageReporting.h"
-#include "HAL/Errors.hpp"
+#include "HAL/Errors.h"
 #include "HAL/Port.h"
 #include "ctre/ctre.h"
 #include "visa/visa.h"
diff --git a/hal/lib/athena/Interrupts.cpp b/hal/lib/athena/Interrupts.cpp
index b461548234..274a3418e1 100644
--- a/hal/lib/athena/Interrupts.cpp
+++ b/hal/lib/athena/Interrupts.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Interrupts.hpp"
+#include "HAL/Interrupts.h"
 #include "ChipObject.h"
 
 extern void remapDigitalSource(bool analogTrigger, uint32_t& pin,
diff --git a/hal/lib/athena/Notifier.cpp b/hal/lib/athena/Notifier.cpp
index 95e9aee20b..26c8397c0c 100644
--- a/hal/lib/athena/Notifier.cpp
+++ b/hal/lib/athena/Notifier.cpp
@@ -5,12 +5,12 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Notifier.hpp"
+#include "HAL/Notifier.h"
 #include <atomic>
 #include <cstdlib>
 #include <mutex>
 #include "ChipObject.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "HAL/cpp/priority_mutex.h"
 
 static const uint32_t kTimerInterruptNumber = 28;
diff --git a/hal/lib/athena/PDP.cpp b/hal/lib/athena/PDP.cpp
index 7df073db1d..e043018948 100644
--- a/hal/lib/athena/PDP.cpp
+++ b/hal/lib/athena/PDP.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/PDP.hpp"
+#include "HAL/PDP.h"
 #include "ctre/PDP.h"
 // static PDP pdp;
 
diff --git a/hal/lib/athena/Power.cpp b/hal/lib/athena/Power.cpp
index 0a6f373cf5..571c5d3625 100644
--- a/hal/lib/athena/Power.cpp
+++ b/hal/lib/athena/Power.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Power.hpp"
+#include "HAL/Power.h"
 #include "ChipObject.h"
 
 static tPower* power = NULL;
diff --git a/hal/lib/athena/Semaphore.cpp b/hal/lib/athena/Semaphore.cpp
index d1b44d58b9..5f7111a3ed 100644
--- a/hal/lib/athena/Semaphore.cpp
+++ b/hal/lib/athena/Semaphore.cpp
@@ -5,9 +5,9 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Semaphore.hpp"
+#include "HAL/Semaphore.h"
 
-#include "Log.hpp"
+#include "Log.h"
 
 // set the logging level
 TLogLevel semaphoreLogLevel = logDEBUG;
diff --git a/hal/lib/athena/SerialPort.cpp b/hal/lib/athena/SerialPort.cpp
index e667dbfa4d..0e3dea3826 100644
--- a/hal/lib/athena/SerialPort.cpp
+++ b/hal/lib/athena/SerialPort.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/SerialPort.hpp"
+#include "HAL/SerialPort.h"
 #include "visa/visa.h"
 
 static uint32_t m_resourceManagerHandle;
diff --git a/hal/lib/athena/Solenoid.cpp b/hal/lib/athena/Solenoid.cpp
index 57a1fb6b47..a0099439a4 100644
--- a/hal/lib/athena/Solenoid.cpp
+++ b/hal/lib/athena/Solenoid.cpp
@@ -5,11 +5,11 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Solenoid.hpp"
+#include "HAL/Solenoid.h"
 
 #include "ChipObject.h"
 #include "FRC_NetworkCommunication/LoadOut.h"
-#include "HAL/Errors.hpp"
+#include "HAL/Errors.h"
 #include "HAL/Port.h"
 #include "ctre/PCM.h"
 
diff --git a/hal/lib/athena/Task.cpp b/hal/lib/athena/Task.cpp
index 3c78c676fd..e34ee35af2 100644
--- a/hal/lib/athena/Task.cpp
+++ b/hal/lib/athena/Task.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Task.hpp"
+#include "HAL/Task.h"
 
 #ifndef OK
 #define OK 0
diff --git a/hal/lib/athena/Utilities.cpp b/hal/lib/athena/Utilities.cpp
index 3338a4133e..189c2ce4d2 100644
--- a/hal/lib/athena/Utilities.cpp
+++ b/hal/lib/athena/Utilities.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Utilities.hpp"
+#include "HAL/Utilities.h"
 #include <time.h>
 
 const int32_t HAL_NO_WAIT = 0;
diff --git a/hal/lib/athena/cpp/Resource.cpp b/hal/lib/athena/cpp/Resource.cpp
index b3c8ca69fe..8a2d0ecd0b 100644
--- a/hal/lib/athena/cpp/Resource.cpp
+++ b/hal/lib/athena/cpp/Resource.cpp
@@ -5,9 +5,9 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/cpp/Resource.hpp"
+#include "HAL/cpp/Resource.h"
 #include <cstddef>
-#include "HAL/Errors.hpp"
+#include "HAL/Errors.h"
 #include "HAL/cpp/priority_mutex.h"
 
 namespace hal {
diff --git a/hal/lib/athena/cpp/Semaphore.cpp b/hal/lib/athena/cpp/Semaphore.cpp
index 61e354167a..64f3ed1c97 100644
--- a/hal/lib/athena/cpp/Semaphore.cpp
+++ b/hal/lib/athena/cpp/Semaphore.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/cpp/Semaphore.hpp"
+#include "HAL/cpp/Semaphore.h"
 
 Semaphore::Semaphore(uint32_t count) { m_count = count; }
 
diff --git a/hal/lib/shared/HAL.cpp b/hal/lib/shared/HAL.cpp
index e4099e48e5..52c7e0719f 100644
--- a/hal/lib/shared/HAL.cpp
+++ b/hal/lib/shared/HAL.cpp
@@ -1,6 +1,6 @@
 // This file must compile on ALL PLATFORMS. Be very careful what you put in
 // here.
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include <cstring>
 #include "FRC_NetworkCommunication/FRCComm.h"
 
diff --git a/wpilibc/athena/include/AnalogInput.h b/wpilibc/athena/include/AnalogInput.h
index e7cb88507f..56b957d412 100644
--- a/wpilibc/athena/include/AnalogInput.h
+++ b/wpilibc/athena/include/AnalogInput.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "LiveWindow/LiveWindowSendable.h"
 #include "PIDSource.h"
 #include "SensorBase.h"
diff --git a/wpilibc/athena/include/AnalogOutput.h b/wpilibc/athena/include/AnalogOutput.h
index 9f4fac87e7..affbe463b1 100644
--- a/wpilibc/athena/include/AnalogOutput.h
+++ b/wpilibc/athena/include/AnalogOutput.h
@@ -9,7 +9,7 @@
 
 #include <cstdint>
 #include <memory>
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "LiveWindow/LiveWindowSendable.h"
 #include "SensorBase.h"
 
diff --git a/wpilibc/athena/include/AnalogTrigger.h b/wpilibc/athena/include/AnalogTrigger.h
index 245258d732..ff28985bb1 100644
--- a/wpilibc/athena/include/AnalogTrigger.h
+++ b/wpilibc/athena/include/AnalogTrigger.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include "AnalogTriggerOutput.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "SensorBase.h"
 
 class AnalogInput;
diff --git a/wpilibc/athena/include/CANJaguar.h b/wpilibc/athena/include/CANJaguar.h
index 132799b577..d68d8ca40d 100644
--- a/wpilibc/athena/include/CANJaguar.h
+++ b/wpilibc/athena/include/CANJaguar.h
@@ -10,8 +10,8 @@
 #include "CAN/can_proto.h"
 #include "CANSpeedController.h"
 #include "ErrorBase.h"
-#include "HAL/HAL.hpp"
-#include "HAL/cpp/Semaphore.hpp"
+#include "HAL/HAL.h"
+#include "HAL/cpp/Semaphore.h"
 #include "LiveWindow/LiveWindowSendable.h"
 #include "MotorSafety.h"
 #include "MotorSafetyHelper.h"
diff --git a/wpilibc/athena/include/Compressor.h b/wpilibc/athena/include/Compressor.h
index 0a8ba64c13..7e7db8610b 100644
--- a/wpilibc/athena/include/Compressor.h
+++ b/wpilibc/athena/include/Compressor.h
@@ -8,7 +8,7 @@
 #ifndef Compressor_H_
 #define Compressor_H_
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "LiveWindow/LiveWindowSendable.h"
 #include "SensorBase.h"
 #include "tables/ITableListener.h"
diff --git a/wpilibc/athena/include/Counter.h b/wpilibc/athena/include/Counter.h
index a679aeea69..aea6f852ba 100644
--- a/wpilibc/athena/include/Counter.h
+++ b/wpilibc/athena/include/Counter.h
@@ -9,7 +9,7 @@
 
 #include "AnalogTriggerOutput.h"
 #include "CounterBase.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "LiveWindow/LiveWindowSendable.h"
 #include "SensorBase.h"
 
diff --git a/wpilibc/athena/include/DriverStation.h b/wpilibc/athena/include/DriverStation.h
index 3f310a3a09..c11f4c0c7e 100644
--- a/wpilibc/athena/include/DriverStation.h
+++ b/wpilibc/athena/include/DriverStation.h
@@ -10,8 +10,8 @@
 #include <atomic>
 #include <condition_variable>
 #include <memory>
-#include "HAL/HAL.hpp"
-#include "HAL/cpp/Semaphore.hpp"
+#include "HAL/HAL.h"
+#include "HAL/cpp/Semaphore.h"
 #include "HAL/cpp/priority_condition_variable.h"
 #include "HAL/cpp/priority_mutex.h"
 #include "RobotState.h"
diff --git a/wpilibc/athena/include/Encoder.h b/wpilibc/athena/include/Encoder.h
index 9312d8b812..45d3bb09f6 100644
--- a/wpilibc/athena/include/Encoder.h
+++ b/wpilibc/athena/include/Encoder.h
@@ -9,7 +9,7 @@
 
 #include "Counter.h"
 #include "CounterBase.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "LiveWindow/LiveWindowSendable.h"
 #include "PIDSource.h"
 #include "SensorBase.h"
diff --git a/wpilibc/athena/include/InterruptableSensorBase.h b/wpilibc/athena/include/InterruptableSensorBase.h
index 45d04dc450..d4d0aeaf70 100644
--- a/wpilibc/athena/include/InterruptableSensorBase.h
+++ b/wpilibc/athena/include/InterruptableSensorBase.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "Resource.h"
 #include "SensorBase.h"
 
diff --git a/wpilibc/athena/include/Preferences.h b/wpilibc/athena/include/Preferences.h
index ba5001adb4..30130d467b 100644
--- a/wpilibc/athena/include/Preferences.h
+++ b/wpilibc/athena/include/Preferences.h
@@ -11,7 +11,7 @@
 #include <string>
 #include <vector>
 #include "ErrorBase.h"
-#include "HAL/cpp/Semaphore.hpp"
+#include "HAL/cpp/Semaphore.h"
 #include "Task.h"
 #include "networktables/NetworkTable.h"
 #include "tables/ITableListener.h"
diff --git a/wpilibc/athena/include/RobotDrive.h b/wpilibc/athena/include/RobotDrive.h
index 29810bfd5e..423b7f0cc8 100644
--- a/wpilibc/athena/include/RobotDrive.h
+++ b/wpilibc/athena/include/RobotDrive.h
@@ -11,7 +11,7 @@
 #include <memory>
 #include <sstream>
 #include "ErrorBase.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "MotorSafety.h"
 #include "MotorSafetyHelper.h"
 
diff --git a/wpilibc/athena/include/SPI.h b/wpilibc/athena/include/SPI.h
index b7ea949606..b5db63587b 100644
--- a/wpilibc/athena/include/SPI.h
+++ b/wpilibc/athena/include/SPI.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "SensorBase.h"
 
 class DigitalOutput;
diff --git a/wpilibc/athena/include/SerialPort.h b/wpilibc/athena/include/SerialPort.h
index ea7d676473..58fe096382 100644
--- a/wpilibc/athena/include/SerialPort.h
+++ b/wpilibc/athena/include/SerialPort.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include "ErrorBase.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 
 /**
  * Driver for the RS-232 serial port on the RoboRIO.
diff --git a/wpilibc/athena/include/SolenoidBase.h b/wpilibc/athena/include/SolenoidBase.h
index 4116f93569..02dfb6d8d4 100644
--- a/wpilibc/athena/include/SolenoidBase.h
+++ b/wpilibc/athena/include/SolenoidBase.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "HAL/Port.h"
 #include "Resource.h"
 #include "SensorBase.h"
diff --git a/wpilibc/athena/include/SpeedController.h b/wpilibc/athena/include/SpeedController.h
index 47ba84371c..bc9bc6c066 100644
--- a/wpilibc/athena/include/SpeedController.h
+++ b/wpilibc/athena/include/SpeedController.h
@@ -7,7 +7,7 @@
 
 #pragma once
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "PIDOutput.h"
 
 /**
diff --git a/wpilibc/athena/src/ADXL345_I2C.cpp b/wpilibc/athena/src/ADXL345_I2C.cpp
index 8714bd7923..5ecb91743b 100644
--- a/wpilibc/athena/src/ADXL345_I2C.cpp
+++ b/wpilibc/athena/src/ADXL345_I2C.cpp
@@ -6,7 +6,7 @@
 /*----------------------------------------------------------------------------*/
 
 #include "ADXL345_I2C.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "I2C.h"
 #include "LiveWindow/LiveWindow.h"
 
diff --git a/wpilibc/athena/src/BuiltInAccelerometer.cpp b/wpilibc/athena/src/BuiltInAccelerometer.cpp
index ec1f590818..db4b40f79f 100644
--- a/wpilibc/athena/src/BuiltInAccelerometer.cpp
+++ b/wpilibc/athena/src/BuiltInAccelerometer.cpp
@@ -6,7 +6,7 @@
 /*----------------------------------------------------------------------------*/
 
 #include "BuiltInAccelerometer.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "LiveWindow/LiveWindow.h"
 #include "WPIErrors.h"
 
diff --git a/wpilibc/athena/src/ControllerPower.cpp b/wpilibc/athena/src/ControllerPower.cpp
index 1c50f275bf..42992c346e 100644
--- a/wpilibc/athena/src/ControllerPower.cpp
+++ b/wpilibc/athena/src/ControllerPower.cpp
@@ -8,8 +8,8 @@
 #include "ControllerPower.h"
 
 #include <stdint.h>
-#include <HAL/HAL.hpp>
-#include <HAL/Power.hpp>
+#include <HAL/HAL.h>
+#include <HAL/Power.h>
 #include "ErrorBase.h"
 
 /**
diff --git a/wpilibc/athena/src/DriverStation.cpp b/wpilibc/athena/src/DriverStation.cpp
index 5d2644f7b0..5c50f48ecd 100644
--- a/wpilibc/athena/src/DriverStation.cpp
+++ b/wpilibc/athena/src/DriverStation.cpp
@@ -8,7 +8,7 @@
 #include "DriverStation.h"
 #include <string.h>
 #include "AnalogInput.h"
-#include "Log.hpp"
+#include "Log.h"
 #include "MotorSafetyHelper.h"
 #include "NetworkCommunication/FRCComm.h"
 #include "Timer.h"
diff --git a/wpilibc/athena/src/I2C.cpp b/wpilibc/athena/src/I2C.cpp
index a8f8b27e69..a356d0a70e 100644
--- a/wpilibc/athena/src/I2C.cpp
+++ b/wpilibc/athena/src/I2C.cpp
@@ -6,8 +6,8 @@
 /*----------------------------------------------------------------------------*/
 
 #include "I2C.h"
-#include "HAL/Digital.hpp"
-#include "HAL/HAL.hpp"
+#include "HAL/Digital.h"
+#include "HAL/HAL.h"
 #include "WPIErrors.h"
 
 /**
diff --git a/wpilibc/athena/src/Internal/HardwareHLReporting.cpp b/wpilibc/athena/src/Internal/HardwareHLReporting.cpp
index 3b1a7b6852..5c7820ec7d 100644
--- a/wpilibc/athena/src/Internal/HardwareHLReporting.cpp
+++ b/wpilibc/athena/src/Internal/HardwareHLReporting.cpp
@@ -6,7 +6,7 @@
 /*----------------------------------------------------------------------------*/
 
 #include "Internal/HardwareHLReporting.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 
 void HardwareHLReporting::ReportScheduler() {
   HALReport(HALUsageReporting::kResourceType_Command,
diff --git a/wpilibc/athena/src/IterativeRobot.cpp b/wpilibc/athena/src/IterativeRobot.cpp
index 7bb61f082a..702f040dfa 100644
--- a/wpilibc/athena/src/IterativeRobot.cpp
+++ b/wpilibc/athena/src/IterativeRobot.cpp
@@ -8,7 +8,7 @@
 #include "IterativeRobot.h"
 
 #include "DriverStation.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "LiveWindow/LiveWindow.h"
 #include "SmartDashboard/SmartDashboard.h"
 #include "networktables/NetworkTable.h"
diff --git a/wpilibc/athena/src/Notifier.cpp b/wpilibc/athena/src/Notifier.cpp
index 08b0ace0d4..81be782f27 100644
--- a/wpilibc/athena/src/Notifier.cpp
+++ b/wpilibc/athena/src/Notifier.cpp
@@ -6,7 +6,7 @@
 /*----------------------------------------------------------------------------*/
 
 #include "Notifier.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "Timer.h"
 #include "Utility.h"
 #include "WPIErrors.h"
diff --git a/wpilibc/athena/src/PIDController.cpp b/wpilibc/athena/src/PIDController.cpp
index 65c1d6d898..970a8159ab 100644
--- a/wpilibc/athena/src/PIDController.cpp
+++ b/wpilibc/athena/src/PIDController.cpp
@@ -8,7 +8,7 @@
 #include "PIDController.h"
 #include <math.h>
 #include <vector>
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "Notifier.h"
 #include "PIDOutput.h"
 #include "PIDSource.h"
diff --git a/wpilibc/athena/src/PWM.cpp b/wpilibc/athena/src/PWM.cpp
index 10afd48214..5468821faa 100644
--- a/wpilibc/athena/src/PWM.cpp
+++ b/wpilibc/athena/src/PWM.cpp
@@ -7,7 +7,7 @@
 
 #include "PWM.h"
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "Resource.h"
 #include "Utility.h"
 #include "WPIErrors.h"
diff --git a/wpilibc/athena/src/PowerDistributionPanel.cpp b/wpilibc/athena/src/PowerDistributionPanel.cpp
index 7049ee126b..0a728a1934 100644
--- a/wpilibc/athena/src/PowerDistributionPanel.cpp
+++ b/wpilibc/athena/src/PowerDistributionPanel.cpp
@@ -6,7 +6,7 @@
 /*----------------------------------------------------------------------------*/
 
 #include "PowerDistributionPanel.h"
-#include "HAL/PDP.hpp"
+#include "HAL/PDP.h"
 #include "LiveWindow/LiveWindow.h"
 #include "WPIErrors.h"
 
diff --git a/wpilibc/athena/src/Preferences.cpp b/wpilibc/athena/src/Preferences.cpp
index 731d5d3ecf..5cd47e04ec 100644
--- a/wpilibc/athena/src/Preferences.cpp
+++ b/wpilibc/athena/src/Preferences.cpp
@@ -7,7 +7,7 @@
 
 #include "Preferences.h"
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "WPIErrors.h"
 
 #include <stdio.h>
diff --git a/wpilibc/athena/src/Relay.cpp b/wpilibc/athena/src/Relay.cpp
index f7bf3ccb14..a47f83a73a 100644
--- a/wpilibc/athena/src/Relay.cpp
+++ b/wpilibc/athena/src/Relay.cpp
@@ -7,7 +7,7 @@
 
 #include "Relay.h"
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "LiveWindow/LiveWindow.h"
 #include "MotorSafetyHelper.h"
 #include "Resource.h"
diff --git a/wpilibc/athena/src/RobotBase.cpp b/wpilibc/athena/src/RobotBase.cpp
index df8c7e10db..bbc933cd1b 100644
--- a/wpilibc/athena/src/RobotBase.cpp
+++ b/wpilibc/athena/src/RobotBase.cpp
@@ -10,7 +10,7 @@
 #include <cstdio>
 #include <cstring>
 #include "DriverStation.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "HLUsageReporting.h"
 #include "Internal/HardwareHLReporting.h"
 #include "RobotState.h"
diff --git a/wpilibc/athena/src/SPI.cpp b/wpilibc/athena/src/SPI.cpp
index ba3960e7e3..b639c0d207 100644
--- a/wpilibc/athena/src/SPI.cpp
+++ b/wpilibc/athena/src/SPI.cpp
@@ -7,7 +7,7 @@
 
 #include "SPI.h"
 
-#include "HAL/Digital.hpp"
+#include "HAL/Digital.h"
 #include "WPIErrors.h"
 
 #include <string.h>
diff --git a/wpilibc/athena/src/SensorBase.cpp b/wpilibc/athena/src/SensorBase.cpp
index c6277ef152..41075e002c 100644
--- a/wpilibc/athena/src/SensorBase.cpp
+++ b/wpilibc/athena/src/SensorBase.cpp
@@ -7,7 +7,7 @@
 
 #include "SensorBase.h"
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "HAL/Port.h"
 #include "NetworkCommunication/LoadOut.h"
 #include "WPIErrors.h"
diff --git a/wpilibc/athena/src/SerialPort.cpp b/wpilibc/athena/src/SerialPort.cpp
index 4c9bea1368..3d1a13f4dd 100644
--- a/wpilibc/athena/src/SerialPort.cpp
+++ b/wpilibc/athena/src/SerialPort.cpp
@@ -8,7 +8,7 @@
 #include "SerialPort.h"
 
 #include <stdarg.h>
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 
 // static ViStatus _VI_FUNCH ioCompleteHandler (ViSession vi, ViEventType
 // eventType, ViEvent event, ViAddr userHandle);
diff --git a/wpilibc/athena/src/Timer.cpp b/wpilibc/athena/src/Timer.cpp
index f3a5142f23..facded105e 100644
--- a/wpilibc/athena/src/Timer.cpp
+++ b/wpilibc/athena/src/Timer.cpp
@@ -10,7 +10,7 @@
 #include <time.h>
 
 #include <iostream>
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "Utility.h"
 
 /**
diff --git a/wpilibc/athena/src/Utility.cpp b/wpilibc/athena/src/Utility.cpp
index d1249debd3..58e2d2ed18 100644
--- a/wpilibc/athena/src/Utility.cpp
+++ b/wpilibc/athena/src/Utility.cpp
@@ -15,7 +15,7 @@
 #include <cstring>
 #include <iostream>
 #include <sstream>
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "Task.h"
 #include "nivision.h"
 
diff --git a/wpilibc/shared/include/Task.h b/wpilibc/shared/include/Task.h
index 4e8fe2ab68..cb70d96b33 100644
--- a/wpilibc/shared/include/Task.h
+++ b/wpilibc/shared/include/Task.h
@@ -11,7 +11,7 @@
 #include <string>
 #include <thread>
 #include "ErrorBase.h"
-#include "HAL/Task.hpp"
+#include "HAL/Task.h"
 
 /**
  * Wrapper class around std::thread that allows changing thread priority
diff --git a/wpilibc/shared/include/Task.inc b/wpilibc/shared/include/Task.inc
index 9eed6cc81d..482034e208 100644
--- a/wpilibc/shared/include/Task.inc
+++ b/wpilibc/shared/include/Task.inc
@@ -6,7 +6,7 @@
 /*----------------------------------------------------------------------------*/
 
 #include <atomic>
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 
 /**
  * Create and launch a task.
diff --git a/wpilibc/sim/include/Counter.h b/wpilibc/sim/include/Counter.h
index 737daccb5a..319a93ce83 100644
--- a/wpilibc/sim/include/Counter.h
+++ b/wpilibc/sim/include/Counter.h
@@ -8,7 +8,7 @@
 #pragma once
 
 #include "CounterBase.h"
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "LiveWindow/LiveWindowSendable.h"
 #include "SensorBase.h"
 
diff --git a/wpilibc/sim/src/DriverStation.cpp b/wpilibc/sim/src/DriverStation.cpp
index 3418af6204..6c14b8e391 100644
--- a/wpilibc/sim/src/DriverStation.cpp
+++ b/wpilibc/sim/src/DriverStation.cpp
@@ -10,7 +10,7 @@
 #include "simulation/MainNode.h"
 //#include "MotorSafetyHelper.h"
 #include <string.h>
-#include "Log.hpp"
+#include "Log.h"
 #include "Utility.h"
 #include "WPIErrors.h"
 #include "boost/mem_fn.hpp"
diff --git a/wpilibj/src/athena/cpp/lib/AccelerometerJNI.cpp b/wpilibj/src/athena/cpp/lib/AccelerometerJNI.cpp
index c84e1216af..38dec67a42 100644
--- a/wpilibj/src/athena/cpp/lib/AccelerometerJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/AccelerometerJNI.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Accelerometer.hpp"
+#include "HAL/Accelerometer.h"
 #include <jni.h>
 #include "edu_wpi_first_wpilibj_hal_AccelerometerJNI.h"
 
diff --git a/wpilibj/src/athena/cpp/lib/AnalogJNI.cpp b/wpilibj/src/athena/cpp/lib/AnalogJNI.cpp
index 7dfc01d38c..22033fb7e8 100644
--- a/wpilibj/src/athena/cpp/lib/AnalogJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/AnalogJNI.cpp
@@ -7,11 +7,11 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_AnalogJNI.h"
 
-#include "HAL/Analog.hpp"
+#include "HAL/Analog.h"
 #include "HALUtil.h"
 
 // set the logging level
diff --git a/wpilibj/src/athena/cpp/lib/CANJNI.cpp b/wpilibj/src/athena/cpp/lib/CANJNI.cpp
index 1cb73d171c..8a391eb220 100644
--- a/wpilibj/src/athena/cpp/lib/CANJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/CANJNI.cpp
@@ -7,12 +7,12 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_can_CANJNI.h"
 
 #include "FRC_NetworkCommunication/CANSessionMux.h"
-#include "HAL/CAN.hpp"
+#include "HAL/CAN.h"
 #include "HALUtil.h"
 
 // set the logging level
diff --git a/wpilibj/src/athena/cpp/lib/CompressorJNI.cpp b/wpilibj/src/athena/cpp/lib/CompressorJNI.cpp
index 2df574fb26..232838b2ba 100644
--- a/wpilibj/src/athena/cpp/lib/CompressorJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/CompressorJNI.cpp
@@ -5,9 +5,9 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "HALUtil.h"
-#include "Log.hpp"
+#include "Log.h"
 #include "edu_wpi_first_wpilibj_hal_CompressorJNI.h"
 
 extern "C" {
diff --git a/wpilibj/src/athena/cpp/lib/CounterJNI.cpp b/wpilibj/src/athena/cpp/lib/CounterJNI.cpp
index ff278fb5c2..6b9705bba9 100644
--- a/wpilibj/src/athena/cpp/lib/CounterJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/CounterJNI.cpp
@@ -7,12 +7,12 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_CounterJNI.h"
 
-#include "HAL/Digital.hpp"
-#include "HAL/Errors.hpp"
+#include "HAL/Digital.h"
+#include "HAL/Errors.h"
 #include "HALUtil.h"
 
 // set the logging level
diff --git a/wpilibj/src/athena/cpp/lib/DIOJNI.cpp b/wpilibj/src/athena/cpp/lib/DIOJNI.cpp
index 53674c4a1b..7d307c4de0 100644
--- a/wpilibj/src/athena/cpp/lib/DIOJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/DIOJNI.cpp
@@ -7,11 +7,11 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_DIOJNI.h"
 
-#include "HAL/Digital.hpp"
+#include "HAL/Digital.h"
 #include "HALUtil.h"
 
 // set the logging level
diff --git a/wpilibj/src/athena/cpp/lib/DigitalGlitchFilterJNI.cpp b/wpilibj/src/athena/cpp/lib/DigitalGlitchFilterJNI.cpp
index a6e2f9232c..6e2bf0377e 100644
--- a/wpilibj/src/athena/cpp/lib/DigitalGlitchFilterJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/DigitalGlitchFilterJNI.cpp
@@ -6,7 +6,7 @@
 /*----------------------------------------------------------------------------*/
 
 #include <jni.h>
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "HALUtil.h"
 
 #include "edu_wpi_first_wpilibj_hal_DigitalGlitchFilterJNI.h"
diff --git a/wpilibj/src/athena/cpp/lib/EncoderJNI.cpp b/wpilibj/src/athena/cpp/lib/EncoderJNI.cpp
index 5cd5d58da7..a4e194b86f 100644
--- a/wpilibj/src/athena/cpp/lib/EncoderJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/EncoderJNI.cpp
@@ -7,12 +7,12 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_EncoderJNI.h"
 
-#include "HAL/Digital.hpp"
-#include "HAL/Errors.hpp"
+#include "HAL/Digital.h"
+#include "HAL/Errors.h"
 #include "HALUtil.h"
 
 // set the logging level
diff --git a/wpilibj/src/athena/cpp/lib/FRCNetworkCommunicationsLibrary.cpp b/wpilibj/src/athena/cpp/lib/FRCNetworkCommunicationsLibrary.cpp
index e9ec7f2f6f..6e6e197b6d 100644
--- a/wpilibj/src/athena/cpp/lib/FRCNetworkCommunicationsLibrary.cpp
+++ b/wpilibj/src/athena/cpp/lib/FRCNetworkCommunicationsLibrary.cpp
@@ -7,9 +7,9 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 #include "edu_wpi_first_wpilibj_communication_FRCNetworkCommunicationsLibrary.h"
 //#include "NetworkCommunication/FRCComm.h"
 //#include "NetworkCommunication/UsageReporting.h"
diff --git a/wpilibj/src/athena/cpp/lib/HALUtil.cpp b/wpilibj/src/athena/cpp/lib/HALUtil.cpp
index dd2732b9bd..e89dd85deb 100644
--- a/wpilibj/src/athena/cpp/lib/HALUtil.cpp
+++ b/wpilibj/src/athena/cpp/lib/HALUtil.cpp
@@ -12,8 +12,8 @@
 #include <cstring>
 #include <string>
 #include "FRC_NetworkCommunication/CANSessionMux.h"
-#include "HAL/HAL.hpp"
-#include "Log.hpp"
+#include "HAL/HAL.h"
+#include "Log.h"
 #include "edu_wpi_first_wpilibj_hal_HALUtil.h"
 #include "errno.h"
 
diff --git a/wpilibj/src/athena/cpp/lib/I2CJNI.cpp b/wpilibj/src/athena/cpp/lib/I2CJNI.cpp
index ffd688bf52..00e071ce31 100644
--- a/wpilibj/src/athena/cpp/lib/I2CJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/I2CJNI.cpp
@@ -7,11 +7,11 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_I2CJNI.h"
 
-#include "HAL/Digital.hpp"
+#include "HAL/Digital.h"
 #include "HALUtil.h"
 
 // set the logging level
diff --git a/wpilibj/src/athena/cpp/lib/InterruptJNI.cpp b/wpilibj/src/athena/cpp/lib/InterruptJNI.cpp
index 1929cee40c..a357a5fc9e 100644
--- a/wpilibj/src/athena/cpp/lib/InterruptJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/InterruptJNI.cpp
@@ -11,9 +11,9 @@
 #include <condition_variable>
 #include <mutex>
 #include <thread>
-#include "Log.hpp"
+#include "Log.h"
 
-#include "HAL/Interrupts.hpp"
+#include "HAL/Interrupts.h"
 #include "HALUtil.h"
 #include "SafeThread.h"
 #include "edu_wpi_first_wpilibj_hal_InterruptJNI.h"
diff --git a/wpilibj/src/athena/cpp/lib/JNIWrapper.cpp b/wpilibj/src/athena/cpp/lib/JNIWrapper.cpp
index b1bf41affe..c20a27e7f3 100644
--- a/wpilibj/src/athena/cpp/lib/JNIWrapper.cpp
+++ b/wpilibj/src/athena/cpp/lib/JNIWrapper.cpp
@@ -7,11 +7,11 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_JNIWrapper.h"
 
-#include "HAL/HAL.hpp"
+#include "HAL/HAL.h"
 
 extern "C" {
 
diff --git a/wpilibj/src/athena/cpp/lib/NotifierJNI.cpp b/wpilibj/src/athena/cpp/lib/NotifierJNI.cpp
index 4e45533ff3..bb5c7489c2 100644
--- a/wpilibj/src/athena/cpp/lib/NotifierJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/NotifierJNI.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Notifier.hpp"
+#include "HAL/Notifier.h"
 #include <assert.h>
 #include <jni.h>
 #include <stdio.h>
@@ -15,7 +15,7 @@
 #include <mutex>
 #include <thread>
 #include "HALUtil.h"
-#include "Log.hpp"
+#include "Log.h"
 #include "SafeThread.h"
 #include "edu_wpi_first_wpilibj_hal_NotifierJNI.h"
 
diff --git a/wpilibj/src/athena/cpp/lib/PDPJNI.cpp b/wpilibj/src/athena/cpp/lib/PDPJNI.cpp
index 8b92625f31..065ac9d893 100644
--- a/wpilibj/src/athena/cpp/lib/PDPJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/PDPJNI.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/PDP.hpp"
+#include "HAL/PDP.h"
 #include "HALUtil.h"
 #include "edu_wpi_first_wpilibj_hal_PDPJNI.h"
 
diff --git a/wpilibj/src/athena/cpp/lib/PWMJNI.cpp b/wpilibj/src/athena/cpp/lib/PWMJNI.cpp
index 004f62dcf1..3bcce97bf9 100644
--- a/wpilibj/src/athena/cpp/lib/PWMJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/PWMJNI.cpp
@@ -7,11 +7,11 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_PWMJNI.h"
 
-#include "HAL/Digital.hpp"
+#include "HAL/Digital.h"
 #include "HALUtil.h"
 
 // set the logging level
diff --git a/wpilibj/src/athena/cpp/lib/PowerJNI.cpp b/wpilibj/src/athena/cpp/lib/PowerJNI.cpp
index faafb9a4e8..4af1470ef8 100644
--- a/wpilibj/src/athena/cpp/lib/PowerJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/PowerJNI.cpp
@@ -5,7 +5,7 @@
 /* the project.                                                               */
 /*----------------------------------------------------------------------------*/
 
-#include "HAL/Power.hpp"
+#include "HAL/Power.h"
 #include <jni.h>
 #include "HALUtil.h"
 #include "edu_wpi_first_wpilibj_hal_PowerJNI.h"
diff --git a/wpilibj/src/athena/cpp/lib/RelayJNI.cpp b/wpilibj/src/athena/cpp/lib/RelayJNI.cpp
index 05fe1026af..88c03b6ba1 100644
--- a/wpilibj/src/athena/cpp/lib/RelayJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/RelayJNI.cpp
@@ -7,11 +7,11 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_RelayJNI.h"
 
-#include "HAL/Digital.hpp"
+#include "HAL/Digital.h"
 #include "HALUtil.h"
 
 // set the logging level
diff --git a/wpilibj/src/athena/cpp/lib/SPIJNI.cpp b/wpilibj/src/athena/cpp/lib/SPIJNI.cpp
index 83a0c38f97..8fb00ec70b 100644
--- a/wpilibj/src/athena/cpp/lib/SPIJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/SPIJNI.cpp
@@ -7,11 +7,11 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_SPIJNI.h"
 
-#include "HAL/Digital.hpp"
+#include "HAL/Digital.h"
 #include "HALUtil.h"
 
 // set the logging level
diff --git a/wpilibj/src/athena/cpp/lib/SerialPortJNI.cpp b/wpilibj/src/athena/cpp/lib/SerialPortJNI.cpp
index 55281d297a..a5887d9b83 100644
--- a/wpilibj/src/athena/cpp/lib/SerialPortJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/SerialPortJNI.cpp
@@ -7,11 +7,11 @@
 
 #include <assert.h>
 #include <jni.h>
-#include "Log.hpp"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_SerialPortJNI.h"
 
-#include "HAL/SerialPort.hpp"
+#include "HAL/SerialPort.h"
 #include "HALUtil.h"
 
 // set the logging level
diff --git a/wpilibj/src/athena/cpp/lib/SolenoidJNI.cpp b/wpilibj/src/athena/cpp/lib/SolenoidJNI.cpp
index c8a70775f9..5a9a030b1c 100644
--- a/wpilibj/src/athena/cpp/lib/SolenoidJNI.cpp
+++ b/wpilibj/src/athena/cpp/lib/SolenoidJNI.cpp
@@ -6,8 +6,8 @@
 /*----------------------------------------------------------------------------*/
 
 #include <jni.h>
-#include "HAL/HAL.hpp"
-#include "Log.hpp"
+#include "HAL/HAL.h"
+#include "Log.h"
 
 #include "edu_wpi_first_wpilibj_hal_SolenoidJNI.h"