diff --git a/libraries/AP_IOMCU/AP_IOMCU.cpp b/libraries/AP_IOMCU/AP_IOMCU.cpp
index 49de80a4e2..90cd8254e3 100644
--- a/libraries/AP_IOMCU/AP_IOMCU.cpp
+++ b/libraries/AP_IOMCU/AP_IOMCU.cpp
@@ -6,6 +6,9 @@
  */
 
 #include "AP_IOMCU.h"
+
+#if HAL_WITH_IO_MCU
+
 #include <AP_Math/AP_Math.h>
 #include <AP_Math/crc.h>
 
@@ -479,3 +482,5 @@ bool AP_IOMCU::check_rcinput(uint32_t &last_frame_us, uint8_t &num_channels, uin
     }
     return false;
 }
+
+#endif // HAL_WITH_IO_MCU
diff --git a/libraries/AP_IOMCU/AP_IOMCU.h b/libraries/AP_IOMCU/AP_IOMCU.h
index 748f445500..bb11eff276 100644
--- a/libraries/AP_IOMCU/AP_IOMCU.h
+++ b/libraries/AP_IOMCU/AP_IOMCU.h
@@ -6,6 +6,9 @@
  */
 
 #include <AP_HAL/AP_HAL.h>
+
+#if HAL_WITH_IO_MCU
+
 #include "ch.h"
 
 class AP_IOMCU {
@@ -172,3 +175,5 @@ private:
     
     bool corked;
 };
+
+#endif // HAL_WITH_IO_MCU