diff --git a/ArduSub/GCS_Mavlink.cpp b/ArduSub/GCS_Mavlink.cpp
index c89a54e9fa..4facb62f80 100644
--- a/ArduSub/GCS_Mavlink.cpp
+++ b/ArduSub/GCS_Mavlink.cpp
@@ -393,7 +393,9 @@ static const ap_message STREAM_EXTRA3_msgs[] = {
 #if HAL_MOUNT_ENABLED
     MSG_GIMBAL_DEVICE_ATTITUDE_STATUS,
 #endif
+#if AP_OPTICALFLOW_ENABLED
     MSG_OPTICAL_FLOW,
+#endif
 #if COMPASS_CAL_ENABLED
     MSG_MAG_CAL_REPORT,
     MSG_MAG_CAL_PROGRESS,