diff --git a/libraries/AC_PID/examples/AC_PID_test/AC_PID_test.pde b/libraries/AC_PID/examples/AC_PID_test/AC_PID_test.pde
index 3deb76cafa..a155e8890d 100644
--- a/libraries/AC_PID/examples/AC_PID_test/AC_PID_test.pde
+++ b/libraries/AC_PID/examples/AC_PID_test/AC_PID_test.pde
@@ -1,7 +1,7 @@
 /*
-	Example of PID library.
-	2012 Code by Jason Short, Randy Mackay. DIYDrones.com
-*/
+ *       Example of PID library.
+ *       2012 Code by Jason Short, Randy Mackay. DIYDrones.com
+ */
 
 // includes
 #include <Arduino_Mega_ISR_Registry.h>
@@ -26,39 +26,39 @@ APM_RC_APM1 APM_RC;
 // setup function
 void setup()
 {
-	Serial.begin(115200);
-	Serial.println("ArduPilot Mega AC_PID library test");
+    Serial.begin(115200);
+    Serial.println("ArduPilot Mega AC_PID library test");
 
-	isr_registry.init();
-	APM_RC.Init(&isr_registry);	 // APM Radio initialization
+    isr_registry.init();
+    APM_RC.Init(&isr_registry);          // APM Radio initialization
 
-	delay(1000);
+    delay(1000);
 }
 
 // main loop
 void loop()
 {
-	// setup (unfortunately must be done here as we cannot create a global AC_PID object)
-	AC_PID pid(0, PSTR("TESTPID_"),  TEST_P, TEST_I, TEST_D, TEST_IMAX * 100);
-	uint16_t radio_in;
-	uint16_t radio_trim;
-	int error;
-	int control;
-	float dt = 1000/50;
+    // setup (unfortunately must be done here as we cannot create a global AC_PID object)
+    AC_PID pid(0, PSTR("TESTPID_"),  TEST_P, TEST_I, TEST_D, TEST_IMAX * 100);
+    uint16_t radio_in;
+    uint16_t radio_trim;
+    int error;
+    int control;
+    float dt = 1000/50;
 
-	// display PID gains
-	Serial.printf("P %f  I %f  D %f  imax %f\n", pid.kP(), pid.kI(), pid.kD(), pid.imax());
+    // display PID gains
+    Serial.printf("P %f  I %f  D %f  imax %f\n", pid.kP(), pid.kI(), pid.kD(), pid.imax());
 
-	// capture radio trim
-	radio_trim = APM_RC.InputCh(0);
+    // capture radio trim
+    radio_trim = APM_RC.InputCh(0);
 
-	while( true ) {
-		radio_in = APM_RC.InputCh(0);
-		error = radio_in - radio_trim;
-		control = pid.get_pid(error, dt);
+    while( true ) {
+        radio_in = APM_RC.InputCh(0);
+        error = radio_in - radio_trim;
+        control = pid.get_pid(error, dt);
 
-		// display pid results
-		Serial.printf("radio: %d\t err: %d\t pid:%d\n", radio_in, error, control);
-		delay(50);
-	}
+        // display pid results
+        Serial.printf("radio: %d\t err: %d\t pid:%d\n", radio_in, error, control);
+        delay(50);
+    }
 }
\ No newline at end of file