diff --git a/ArduCopter/heli.pde b/ArduCopter/heli.pde
index 2f39533114..5b1a707b94 100644
--- a/ArduCopter/heli.pde
+++ b/ArduCopter/heli.pde
@@ -234,7 +234,7 @@ static void heli_move_swash(int roll_out, int pitch_out, int coll_out, int yaw_o
 static void init_motors_out()
 {
 	#if INSTANT_PWM == 0
-    APM_RC.SetFastOutputChannels( MSK_CH_1 | MSK_CH_2 | MSK_CH_3 | MSK_CH_4 );
+    APM_RC.SetFastOutputChannels( _BV(CH_1) | _BV(CH_2) | _BV(CH_3) | _BV(CH_4) );
 	#endif
 }
 
diff --git a/ArduCopter/motors_hexa.pde b/ArduCopter/motors_hexa.pde
index aed18d958d..fc80a31c2c 100644
--- a/ArduCopter/motors_hexa.pde
+++ b/ArduCopter/motors_hexa.pde
@@ -5,8 +5,8 @@
 static void init_motors_out()
 {
 	#if INSTANT_PWM == 0
-    APM_RC.SetFastOutputChannels( MSK_CH_1 | MSK_CH_2 | MSK_CH_3 | MSK_CH_4
-                                | MSK_CH_7 | MSK_CH_8 );
+    APM_RC.SetFastOutputChannels( _BV(CH_1) | _BV(CH_2) | _BV(CH_3) | _BV(CH_4)
+                                | _BV(CH_7) | _BV(CH_8) );
 	#endif
 }
 
diff --git a/ArduCopter/motors_octa.pde b/ArduCopter/motors_octa.pde
index c7705b43a5..929d08be64 100644
--- a/ArduCopter/motors_octa.pde
+++ b/ArduCopter/motors_octa.pde
@@ -5,8 +5,8 @@
 static void init_motors_out()
 {
 	#if INSTANT_PWM == 0
-    APM_RC.SetFastOutputChannels( MSK_CH_1 | MSK_CH_2 | MSK_CH_3 | MSK_CH_4
-                                | MSK_CH_7 | MSK_CH_8 | MSK_CH_10 | MSK_CH_11 );
+    APM_RC.SetFastOutputChannels( _BV(CH_1) | _BV(CH_2) | _BV(CH_3) | _BV(CH_4)
+                                | _BV(CH_7) | _BV(CH_8) | _BV(CH_10) | _BV(CH_11) );
 	#endif
 }
 
diff --git a/ArduCopter/motors_octa_quad.pde b/ArduCopter/motors_octa_quad.pde
index 732dcdf64d..519d09e4b5 100644
--- a/ArduCopter/motors_octa_quad.pde
+++ b/ArduCopter/motors_octa_quad.pde
@@ -5,8 +5,8 @@
 static void init_motors_out()
 {
 	#if INSTANT_PWM == 0
-    APM_RC.SetFastOutputChannels( MSK_CH_1 | MSK_CH_2 | MSK_CH_3 | MSK_CH_4
-                                | MSK_CH_7 | MSK_CH_8 | MSK_CH_10 | MSK_CH_11 );
+    APM_RC.SetFastOutputChannels( _BV(CH_1) | _BV(CH_2) | _BV(CH_3) | _BV(CH_4)
+                                | _BV(CH_7) | _BV(CH_8) | _BV(CH_10) | _BV(CH_11) );
 	#endif
 }
 
diff --git a/ArduCopter/motors_quad.pde b/ArduCopter/motors_quad.pde
index 5bcf2b740b..849ecec2c2 100644
--- a/ArduCopter/motors_quad.pde
+++ b/ArduCopter/motors_quad.pde
@@ -5,7 +5,7 @@
 static void init_motors_out()
 {
 	#if INSTANT_PWM == 0
-    APM_RC.SetFastOutputChannels( MSK_CH_1 | MSK_CH_2 | MSK_CH_3 | MSK_CH_4 );
+    APM_RC.SetFastOutputChannels( _BV(CH_1) | _BV(CH_2) | _BV(CH_3) | _BV(CH_4) );
 	#endif
 }
 
diff --git a/ArduCopter/motors_tri.pde b/ArduCopter/motors_tri.pde
index 849eb1ab12..ec752816b1 100644
--- a/ArduCopter/motors_tri.pde
+++ b/ArduCopter/motors_tri.pde
@@ -4,7 +4,7 @@
 static void init_motors_out()
 {
 	#if INSTANT_PWM == 0
-    APM_RC.SetFastOutputChannels( MSK_CH_1 | MSK_CH_2 | MSK_CH_4 );
+    APM_RC.SetFastOutputChannels( _BV(CH_1) | _BV(CH_2) | _BV(CH_4) );
 	#endif
 }
 
diff --git a/ArduCopter/motors_y6.pde b/ArduCopter/motors_y6.pde
index fdd0f74417..6cbf7bbc06 100644
--- a/ArduCopter/motors_y6.pde
+++ b/ArduCopter/motors_y6.pde
@@ -7,8 +7,8 @@
 static void init_motors_out()
 {
 	#if INSTANT_PWM == 0
-    APM_RC.SetFastOutputChannels( MSK_CH_1 | MSK_CH_2 | MSK_CH_3 | MSK_CH_4
-                                | MSK_CH_7 | MSK_CH_8 );
+    APM_RC.SetFastOutputChannels( _BV(CH_1) | _BV(CH_2) | _BV(CH_3) | _BV(CH_4)
+                                | _BV(CH_7) | _BV(CH_8) );
 	#endif
 }
 
diff --git a/libraries/APM_RC/APM_RC.h b/libraries/APM_RC/APM_RC.h
index e9a00e2c85..7f72b1b183 100644
--- a/libraries/APM_RC/APM_RC.h
+++ b/libraries/APM_RC/APM_RC.h
@@ -21,20 +21,6 @@
 #define CH_10 9
 #define CH_11 10
 
-#define MSK_CH_1 (1 << CH_1)
-#define MSK_CH_2 (1 << CH_2)
-#define MSK_CH_3 (1 << CH_3)
-#define MSK_CH_4 (1 << CH_4)
-#define MSK_CH_5 (1 << CH_5)
-#define MSK_CH_6 (1 << CH_6)
-#define MSK_CH_7 (1 << CH_7)
-#define MSK_CH_8 (1 << CH_8)
-#define MSK_CH_9 (1 << CH_9)
-#define MSK_CH_10 (1 << CH_10)
-#define MSK_CH_11 (1 << CH_11)
-
-
-
 
 #define NUM_CHANNELS 8
 
diff --git a/libraries/APM_RC/APM_RC_APM1.cpp b/libraries/APM_RC/APM_RC_APM1.cpp
index b2aa1464f1..1a480832f4 100644
--- a/libraries/APM_RC/APM_RC_APM1.cpp
+++ b/libraries/APM_RC/APM_RC_APM1.cpp
@@ -216,16 +216,16 @@ void APM_RC_APM1::Force_Out6_Out7(void)
 
 void APM_RC_APM1::SetFastOutputChannels(uint32_t chmask)
 {
-    if ((chmask & ( MSK_CH_1 | MSK_CH_2 | MSK_CH_9)) != 0)
+    if ((chmask & ( _BV(CH_1) | _BV(CH_2) | _BV(CH_9))) != 0)
         _set_speed_ch1_ch2_ch9(OUTPUT_SPEED_400HZ);
 
-    if ((chmask & ( MSK_CH_3 | MSK_CH_4 | MSK_CH_10 )) != 0)
+    if ((chmask & ( _BV(CH_3) | _BV(CH_4) | _BV(CH_10))) != 0)
         _set_speed_ch3_ch4_ch10(OUTPUT_SPEED_400HZ);
 
-    if ((chmask & ( MSK_CH_5 | MSK_CH_6 )) != 0)
+    if ((chmask & ( _BV(CH_5) | _BV(CH_6))) != 0)
         _set_speed_ch5_ch6(OUTPUT_SPEED_400HZ);
 
-    if ((chmask & ( MSK_CH_7 | MSK_CH_8 | MSK_CH_11 )) != 0)
+    if ((chmask & ( _BV(CH_7) | _BV(CH_8) | _BV(CH_11))) != 0)
         _set_speed_ch7_ch8_ch11(OUTPUT_SPEED_400HZ);
 
 }
diff --git a/libraries/APM_RC/APM_RC_APM2.cpp b/libraries/APM_RC/APM_RC_APM2.cpp
index 191febb1f3..ee7b55f50f 100644
--- a/libraries/APM_RC/APM_RC_APM2.cpp
+++ b/libraries/APM_RC/APM_RC_APM2.cpp
@@ -197,13 +197,13 @@ void APM_RC_APM2::Force_Out6_Out7(void) { }
 
 void APM_RC_APM2::SetFastOutputChannels(uint32_t chmask)
 {
-    if ((chmask & ( MSK_CH_1 | MSK_CH_2 )) != 0)
+    if ((chmask & ( _BV(CH_1) | _BV(CH_2))) != 0)
         _set_speed_ch1_ch2(OUTPUT_SPEED_400HZ);
 
-    if ((chmask & ( MSK_CH_3 | MSK_CH_4 | MSK_CH_5 )) != 0)
+    if ((chmask & ( _BV(CH_3) | _BV(CH_4) | _BV(CH_5))) != 0)
         _set_speed_ch3_ch4_ch5(OUTPUT_SPEED_400HZ);
 
-    if ((chmask & ( MSK_CH_6 | MSK_CH_7 | MSK_CH_8 )) != 0)
+    if ((chmask & ( _BV(CH_6) | _BV(CH_7) | _BV(CH_8))) != 0)
         _set_speed_ch6_ch7_ch8(OUTPUT_SPEED_400HZ);
 }