diff --git a/libraries/AP_OpticalFlow/AP_OpticalFlow.cpp b/libraries/AP_OpticalFlow/AP_OpticalFlow.cpp
index be86676d59..0a5c89aa66 100644
--- a/libraries/AP_OpticalFlow/AP_OpticalFlow.cpp
+++ b/libraries/AP_OpticalFlow/AP_OpticalFlow.cpp
@@ -14,6 +14,7 @@
 #include "AP_OpticalFlow_UPFLOW.h"
 #include <AP_Logger/AP_Logger.h>
 #include <GCS_MAVLink/GCS.h>
+#include <AP_AHRS/AP_AHRS.h>
 
 extern const AP_HAL::HAL& hal;
 
diff --git a/libraries/AP_OpticalFlow/AP_OpticalFlow_Calibrator.cpp b/libraries/AP_OpticalFlow/AP_OpticalFlow_Calibrator.cpp
index a23397881e..6b28d68d4c 100644
--- a/libraries/AP_OpticalFlow/AP_OpticalFlow_Calibrator.cpp
+++ b/libraries/AP_OpticalFlow/AP_OpticalFlow_Calibrator.cpp
@@ -22,6 +22,7 @@
 
 #include <GCS_MAVLink/GCS.h>
 #include <AP_Logger/AP_Logger.h>
+#include <AP_AHRS/AP_AHRS.h>
 
 const uint32_t AP_OPTICALFLOW_CAL_TIMEOUT_SEC = 120;        // calibration timesout after 120 seconds
 const uint32_t AP_OPTICALFLOW_CAL_STATUSINTERVAL_SEC = 3;   // status updates printed at 3 second intervals
diff --git a/libraries/AP_OpticalFlow/AP_OpticalFlow_Calibrator.h b/libraries/AP_OpticalFlow/AP_OpticalFlow_Calibrator.h
index 13b9c5c0dc..3f894ce475 100644
--- a/libraries/AP_OpticalFlow/AP_OpticalFlow_Calibrator.h
+++ b/libraries/AP_OpticalFlow/AP_OpticalFlow_Calibrator.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <AP_Math/AP_Math.h>
+#include <AP_Logger/AP_Logger_config.h>
 
 #define AP_OPTICALFLOW_CAL_MAX_SAMPLES 50  // number of samples required before calibration begins
 
@@ -53,8 +54,10 @@ private:
     // calculate mean squared residual for all samples of a single axis (0 or 1) given a scalar parameter
     float calc_mean_squared_residuals(uint8_t axis, float scalar) const;
 
+#if HAL_LOGGING_ENABLED
     // log a sample
     void log_sample(uint8_t axis, uint8_t sample_num, float flow_rate, float body_rate, float los_pred);
+#endif
 
     // calibration states
     enum class CalState {