diff --git a/libraries/AP_HAL_AVR/PWMOutput.h b/libraries/AP_HAL_AVR/PWMOutput.h
index cb1b9a7136..9cfbc8655a 100644
--- a/libraries/AP_HAL_AVR/PWMOutput.h
+++ b/libraries/AP_HAL_AVR/PWMOutput.h
@@ -3,6 +3,7 @@
 #define __AP_HAL_AVR_PWM_OUTPUT_H__
 
 #include <AP_HAL.h>
+#include "AP_HAL_AVR_Namespace.h"
 
 class AP_HAL_AVR::APM1PWMOutput : public AP_HAL::PWMOutput {
 public:
diff --git a/libraries/AP_HAL_AVR/SPIDriver.h b/libraries/AP_HAL_AVR/SPIDriver.h
index 0b0131a5da..60fc5ea471 100644
--- a/libraries/AP_HAL_AVR/SPIDriver.h
+++ b/libraries/AP_HAL_AVR/SPIDriver.h
@@ -3,6 +3,7 @@
 #define __AP_HAL_ARDUINO_SPI_DRIVER_H__
 
 #include <AP_HAL.h>
+#include "AP_HAL_AVR_Namespace.h"
 
 class AP_HAL_AVR::ArduinoSPIDriver : public AP_HAL::SPIDriver {
 public:
diff --git a/libraries/AP_HAL_AVR/Storage.h b/libraries/AP_HAL_AVR/Storage.h
index cbd959a08a..41f7e15b15 100644
--- a/libraries/AP_HAL_AVR/Storage.h
+++ b/libraries/AP_HAL_AVR/Storage.h
@@ -4,6 +4,7 @@
 #define __AP_HAL_AVR_STORAGE_H__
 
 #include <AP_HAL.h>
+#include "AP_HAL_AVR_Namespace.h"
 
 class AP_HAL_AVR::AVREEPROMStorage : public AP_HAL::Storage {
 public:
diff --git a/libraries/AP_HAL_AVR/UARTDriver.h b/libraries/AP_HAL_AVR/UARTDriver.h
index 2454aaffd7..4fe41472c2 100644
--- a/libraries/AP_HAL_AVR/UARTDriver.h
+++ b/libraries/AP_HAL_AVR/UARTDriver.h
@@ -3,6 +3,9 @@
 #define __AP_HAL_AVR_UART_DRIVER_H__
 
 #include <stdint.h>
+#include <stdarg.h>
+
+#include <avr/interrupt.h>
 
 #include <AP_Common.h>
 #include <AP_HAL.h>