diff --git a/libraries/AP_Vehicle/AP_Vehicle.cpp b/libraries/AP_Vehicle/AP_Vehicle.cpp
index 05b4296510..b0033431fa 100644
--- a/libraries/AP_Vehicle/AP_Vehicle.cpp
+++ b/libraries/AP_Vehicle/AP_Vehicle.cpp
@@ -511,13 +511,13 @@ void AP_Vehicle::update_dynamic_notch(AP_InertialSensor::HarmonicNotch &notch)
                 float notches[INS_MAX_NOTCHES];
                 const uint8_t num_notches = AP::esc_telem().get_motor_frequencies_hz(notch.num_dynamic_notches, notches);
                 // ESC telemetry will return 0 for missing data, but only after 1s
-                for (uint8_t i = 0; i < notch.num_dynamic_notches; i++) {
+                for (uint8_t i = 0; i < num_notches; i++) {
                     if (!is_zero(notches[i])) {
                         notches[i] =  MAX(ref_freq, notches[i]);
                     }
                 }
                 if (num_notches > 0) {
-                    notch.update_frequencies_hz(notch.num_dynamic_notches, notches);
+                    notch.update_frequencies_hz(num_notches, notches);
                 } else {    // throttle fallback
                     update_throttle_notch(notch);
                 }