diff --git a/libraries/AP_Vehicle/AP_Vehicle.cpp b/libraries/AP_Vehicle/AP_Vehicle.cpp
index 506a48f11d..5282e01e2f 100644
--- a/libraries/AP_Vehicle/AP_Vehicle.cpp
+++ b/libraries/AP_Vehicle/AP_Vehicle.cpp
@@ -515,8 +515,8 @@ void AP_Vehicle::update_dynamic_notch(AP_InertialSensor::HarmonicNotch &notch)
             // set the harmonic notch filter frequency scaled on measured frequency
             if (notch.params.hasOption(HarmonicNotchFilterParams::Options::DynamicHarmonic)) {
                 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
+                const uint8_t num_notches = AP::esc_telem().get_motor_frequencies_hz(INS_MAX_NOTCHES, notches);
                 for (uint8_t i = 0; i < num_notches; i++) {
                     if (!is_zero(notches[i])) {
                         notches[i] =  MAX(ref_freq, notches[i]);