diff --git a/libraries/Filter/HarmonicNotchFilter.cpp b/libraries/Filter/HarmonicNotchFilter.cpp
index 3047cafd45..82ae789ba5 100644
--- a/libraries/Filter/HarmonicNotchFilter.cpp
+++ b/libraries/Filter/HarmonicNotchFilter.cpp
@@ -22,7 +22,6 @@
 #include <GCS_MAVLink/GCS.h>
 
 #define HNF_MAX_FILTERS HAL_HNF_MAX_FILTERS // must be even for double-notch filters
-#define HNF_MAX_HARMONICS 8
 
 // table of user settable parameters
 const AP_Param::GroupInfo HarmonicNotchFilterParams::var_info[] = {
@@ -61,7 +60,22 @@ const AP_Param::GroupInfo HarmonicNotchFilterParams::var_info[] = {
     // @Param: HMNCS
     // @DisplayName: Harmonic Notch Filter harmonics
     // @Description: Bitmask of harmonic frequencies to apply Harmonic Notch Filter to. This option takes effect on the next reboot. A value of 0 disables this filter. The first harmonic refers to the base frequency.
-    // @Bitmask: 0:1st harmonic,1:2nd harmonic,2:3rd harmonic,3:4th hamronic,4:5th harmonic,5:6th harmonic,6:7th harmonic,7:8th harmonic
+    // @Bitmask: 0:  1st harmonic
+    // @Bitmask: 1:  2nd harmonic
+    // @Bitmask: 2:  3rd harmonic
+    // @Bitmask: 3:  4th harmonic
+    // @Bitmask: 4:  5th harmonic
+    // @Bitmask: 5:  6th harmonic
+    // @Bitmask: 6:  7th harmonic
+    // @Bitmask: 7:  8th harmonic
+    // @Bitmask: 8:  9th harmonic
+    // @Bitmask: 9:  10th harmonic
+    // @Bitmask: 10: 11th harmonic
+    // @Bitmask: 11: 12th harmonic
+    // @Bitmask: 12: 13th harmonic
+    // @Bitmask: 13: 14th harmonic
+    // @Bitmask: 14: 15th harmonic
+    // @Bitmask: 15: 16th harmonic
     // @User: Advanced
     // @RebootRequired: True
     AP_GROUPINFO("HMNCS", 5, HarmonicNotchFilterParams, _harmonics, 3),
@@ -143,7 +157,7 @@ void HarmonicNotchFilter<T>::init(float sample_freq_hz, float center_freq_hz, fl
   allocate a collection of, at most HNF_MAX_FILTERS, notch filters to be managed by this harmonic notch filter
  */
 template <class T>
-void HarmonicNotchFilter<T>::allocate_filters(uint8_t num_notches, uint8_t harmonics, uint8_t composite_notches)
+void HarmonicNotchFilter<T>::allocate_filters(uint8_t num_notches, uint32_t harmonics, uint8_t composite_notches)
 {
     _composite_notches = MIN(composite_notches, 3);
     _num_harmonics = __builtin_popcount(harmonics);
@@ -327,6 +341,11 @@ HarmonicNotchFilterParams::HarmonicNotchFilterParams(void)
     AP_Param::setup_object_defaults(this, var_info);
 }
 
+void HarmonicNotchFilterParams::init()
+{
+    _harmonics.convert_parameter_width(AP_PARAM_INT8);
+}
+
 /*
   save changed parameters
  */
diff --git a/libraries/Filter/HarmonicNotchFilter.h b/libraries/Filter/HarmonicNotchFilter.h
index 064365f0b2..7de4df799d 100644
--- a/libraries/Filter/HarmonicNotchFilter.h
+++ b/libraries/Filter/HarmonicNotchFilter.h
@@ -19,7 +19,7 @@
 #include <AP_Param/AP_Param.h>
 #include "NotchFilter.h"
 
-#define HNF_MAX_HARMONICS 8
+#define HNF_MAX_HARMONICS 16
 
 /*
   a filter that manages a set of notch filters targetted at a fundamental center frequency
@@ -30,7 +30,7 @@ class HarmonicNotchFilter {
 public:
     ~HarmonicNotchFilter();
     // allocate a bank of notch filters for this harmonic notch filter
-    void allocate_filters(uint8_t num_notches, uint8_t harmonics, uint8_t composite_notches);
+    void allocate_filters(uint8_t num_notches, uint32_t harmonics, uint8_t composite_notches);
     // expand filter bank with new filters
     void expand_filter_count(uint8_t num_notches);
     // initialize the underlying filters using the provided filter parameters
@@ -56,7 +56,7 @@ private:
     // quality factor of each filter
     float _Q;
     // a bitmask of the harmonics to use
-    uint8_t _harmonics;
+    uint32_t _harmonics;
     // number of notches that make up a composite notch
     uint8_t _composite_notches;
     // number of allocated filters
@@ -95,16 +95,19 @@ public:
     };
 
     HarmonicNotchFilterParams(void);
+
+    void init();
+
     // set the fundamental center frequency of the harmonic notch
     void set_center_freq_hz(float center_freq) { _center_freq_hz.set(center_freq); }
     // set the bandwidth of the harmonic notch
     void set_bandwidth_hz(float bandwidth_hz) { _bandwidth_hz.set(bandwidth_hz); }
     // harmonics enabled on the harmonic notch
-    uint8_t harmonics(void) const { return _harmonics; }
+    uint32_t harmonics(void) const { return _harmonics; }
     // set the harmonics value
-    void set_harmonics(uint8_t hmncs) { _harmonics.set(hmncs); }
+    void set_harmonics(uint32_t hmncs) { _harmonics.set(hmncs); }
     // has the user set the harmonics value
-    void set_default_harmonics(uint8_t hmncs) { _harmonics.set_default(hmncs); }
+    void set_default_harmonics(uint32_t hmncs) { _harmonics.set_default(hmncs); }
     // reference value of the harmonic notch
     float reference(void) const { return _reference; }
     void set_reference(float ref) { _reference.set(ref); }
@@ -125,7 +128,7 @@ public:
 
 private:
     // configured notch harmonics
-    AP_Int8 _harmonics;
+    AP_Int32 _harmonics;
     // notch reference value
     AP_Float _reference;
     // notch dynamic tracking mode