diff --git a/conf/autopilot/subsystems/fixedwing/imu_ppzuav.makefile b/conf/autopilot/subsystems/fixedwing/imu_ppzuav.makefile
index 8f224a9166..dee6b9aaf9 100644
--- a/conf/autopilot/subsystems/fixedwing/imu_ppzuav.makefile
+++ b/conf/autopilot/subsystems/fixedwing/imu_ppzuav.makefile
@@ -7,10 +7,10 @@ IMU_PPZUAVIMU_SRCS    = $(SRC_SUBSYSTEMS)/imu.c             \
 
 
 IMU_PPZUAVIMU_CFLAGS += -DUSE_I2C
-ifdef STM32
+ifeq ($(ARCH), stm32)
 	IMU_PPZUAVIMU_CFLAGS += -DUSE_I2C2
 	IMU_PPZUAVIMU_CFLAGS += -DPPZUAVIMU_I2C_DEVICE=i2c2
-else
+else ifeq ($(ARCH), lpc21)
 	IMU_PPZUAVIMU_CFLAGS += -DUSE_I2C0
 	IMU_PPZUAVIMU_CFLAGS += -DPPZUAVIMU_I2C_DEVICE=i2c0
 endif