diff --git a/libraries/AP_Compass/AP_Compass_HIL.cpp b/libraries/AP_Compass/AP_Compass_HIL.cpp
index f57d7f5320..1e3187a343 100644
--- a/libraries/AP_Compass/AP_Compass_HIL.cpp
+++ b/libraries/AP_Compass/AP_Compass_HIL.cpp
@@ -16,7 +16,7 @@
 bool AP_Compass_HIL::read()
 {
 	// values set by setHIL function
-	last_update = millis();  // record time of update
+	last_update = micros();  // record time of update
 	return true;
 }
 
diff --git a/libraries/AP_Compass/AP_Compass_HMC5843.cpp b/libraries/AP_Compass/AP_Compass_HMC5843.cpp
index dc452baad7..a34bf8c424 100644
--- a/libraries/AP_Compass/AP_Compass_HMC5843.cpp
+++ b/libraries/AP_Compass/AP_Compass_HMC5843.cpp
@@ -279,7 +279,7 @@ bool AP_Compass_HMC5843::read()
    mag_y *= calibration[1];
    mag_z *= calibration[2];
 
-   last_update = millis();  // record time of update
+   last_update = micros();  // record time of update
    // rotate and offset the magnetometer values
    // XXX this could well be done in common code...