diff --git a/ArduPlane/ArduPlane.pde b/ArduPlane/ArduPlane.pde
index 1c626b40d3..3046aa8178 100644
--- a/ArduPlane/ArduPlane.pde
+++ b/ArduPlane/ArduPlane.pde
@@ -38,7 +38,7 @@ version 2.1 of the License, or (at your option) any later version.
 #include <AP_Baro.h>        // ArduPilot barometer library
 #include <AP_Compass.h>     // ArduPilot Mega Magnetometer Library
 #include <AP_Math.h>        // ArduPilot Mega Vector/Matrix math Library
-#include <AP_InertialSensor.h> // Inertial Sensor (uncalibated IMU) Library
+#include <AP_InertialSensor.h> // Inertial Sensor (uncalibrated IMU) Library
 #include <AP_IMU.h>         // ArduPilot Mega IMU Library
 #include <AP_AHRS.h>         // ArduPilot Mega DCM Library
 #include <PID.h>            // PID library
diff --git a/ArduPlane/Parameters.pde b/ArduPlane/Parameters.pde
index d1bb21685e..6c1c2849fd 100644
--- a/ArduPlane/Parameters.pde
+++ b/ArduPlane/Parameters.pde
@@ -36,7 +36,7 @@ static const AP_Param::Info var_info[] PROGMEM = {
     
     // @Param: KFF_RDDRMIX
 	// @DisplayName: Rudder Mix
-	// @Description: The ammount of rudder mix to apply during aileron movement 0 = 0 %, 1 = 100%
+	// @Description: The amount of rudder mix to apply during aileron movement 0 = 0 %, 1 = 100%
 	// @Range: 0 1
 	// @Increment: 0.01
 	// @User: Standard
diff --git a/libraries/AP_IMU/IMU.cpp b/libraries/AP_IMU/IMU.cpp
index 838314857c..8da7ce22e8 100644
--- a/libraries/AP_IMU/IMU.cpp
+++ b/libraries/AP_IMU/IMU.cpp
@@ -12,7 +12,7 @@ const AP_Param::GroupInfo IMU::var_info[] PROGMEM = {
 /* Empty implementations for the IMU functions.
  * Although these will never be used, in certain situations with
  * optimizations turned off, having empty implementations in an object
- * file will help satisify the linker.
+ * file will help satisfy the linker.
  */
 
 IMU::IMU () {}