diff --git a/src/BME280.cpp b/src/BME280.cpp
index b901d3f..b9c096f 100644
--- a/src/BME280.cpp
+++ b/src/BME280.cpp
@@ -28,6 +28,7 @@ of www.endmemo.com, altitude equation courtesy of NOAA, and dew point equation
 courtesy of Brian McNoldy at http://andrew.rsmas.miami.edu.
  */
 
+#include <Arduino.h>
 #include <Wire.h>
 
 #include "BME280.h"
diff --git a/src/BME280I2C.cpp b/src/BME280I2C.cpp
index 242127b..27e66f8 100644
--- a/src/BME280I2C.cpp
+++ b/src/BME280I2C.cpp
@@ -28,6 +28,7 @@ of www.endmemo.com, altitude equation courtesy of NOAA, and dew point equation
 courtesy of Brian McNoldy at http://andrew.rsmas.miami.edu.
  */
 
+#include <Arduino.h>
 #include <Wire.h>
 
 #include "BME280I2C.h"