diff --git a/conf/autopilot/subsystems/fixedwing/imu_analog.makefile b/conf/autopilot/subsystems/fixedwing/imu_analog.makefile
index b319b6d507..31fe680501 100644
--- a/conf/autopilot/subsystems/fixedwing/imu_analog.makefile
+++ b/conf/autopilot/subsystems/fixedwing/imu_analog.makefile
@@ -44,7 +44,7 @@
 
 ifeq ($(ARCH), lpc21)
 imu_CFLAGS += -DADC
-imu_CFLAGS += -DUSE_$(GYRO_P) -DUSE_$(GYRO_Q) -DUSE_ADC_$(GYRO_R)
+imu_CFLAGS += -DUSE_$(GYRO_P) -DUSE_$(GYRO_Q) -DUSE_$(GYRO_R)
 imu_CFLAGS += -DUSE_$(ACCEL_X) -DUSE_$(ACCEL_y) -DUSE_$(ACCEL_Z)
 
 imu_CFLAGS += -DADC_CHANNEL_GYRO_P=$(GYRO_P) -DADC_CHANNEL_GYRO_Q=$(GYRO_Q) -DADC_CHANNEL_GYRO_R=$(GYRO_R)