diff --git a/plugin/chorus.cpp b/plugin/chorus.cpp
index f8f4372..1f6b779 100644
--- a/plugin/chorus.cpp
+++ b/plugin/chorus.cpp
@@ -55,14 +55,14 @@ Chorus::~Chorus() {
     delete postFilter2r;
 }
 
-void Chorus::run(const float* input, float** outputs, uint32_t frames) {
+void Chorus::run(float* input, float** outputs, uint32_t frames) {
     // actual effects here
 
     // FIXME add highpass filter
 
     // now run the DSP
     float s0 = 0, s1 = 0;
-    float lfoMod, dly1, frac;
+    float lfoMod, dly1, frac, flt;
     uint16_t tap, delay;
 
     for (uint32_t i = 0; i < frames; i++) {
@@ -70,6 +70,10 @@ void Chorus::run(const float* input, float** outputs, uint32_t frames) {
         fastPhase += fastOmega;
         if (fastPhase > 6.283) fastPhase -= 6.283;
 
+        flt = ((hpdelay - input[i]) * hpcut) + input[i];
+        hpdelay = flt;
+        input[i] += (flt * hpgain);
+
         ram[delayptr] = input[i];
 
 #define BASE 0.005
@@ -115,6 +119,24 @@ void Chorus::run(const float* input, float** outputs, uint32_t frames) {
 }
 
 void Chorus::setHpf(uint8_t mode) {
+    switch (mode) {
+        case 0x00:
+            hpcut = 0.91245;
+            hpgain = -1;
+            break;
+        case 0x08:
+            hpcut = 0.97097;
+            hpgain = -1;
+            break;
+        case 0x10:
+            hpcut = 1;
+            hpgain = 0;
+            break;
+        case 0x18:
+            hpcut = 0.99088;
+            hpgain = 1;
+            break;
+    }
 }
 
 void Chorus::setChorus(uint8_t mode) {
diff --git a/plugin/chorus.hpp b/plugin/chorus.hpp
index 8dc7328..5596fc2 100644
--- a/plugin/chorus.hpp
+++ b/plugin/chorus.hpp
@@ -33,7 +33,7 @@ class Chorus {
    public:
     Chorus();
     ~Chorus();
-    void run(const float* input, float** outputs, uint32_t frames);
+    void run( float* input, float** outputs, uint32_t frames);
     void setHpf(uint8_t mode);
     void setChorus(uint8_t mode);
 
@@ -47,6 +47,8 @@ class Chorus {
     float* lpfIn;
     float *lpfOut1, *lpfOut2;
 
+    float hpdelay=0, hpcut=0, hpgain=1;
+
     SVF *postFilter1l, *postFilter2l, *postFilter1r, *postFilter2r;
 };
 #endif
diff --git a/plugin/module.cpp b/plugin/module.cpp
index 5c8a8df..3c4d7a5 100644
--- a/plugin/module.cpp
+++ b/plugin/module.cpp
@@ -43,6 +43,7 @@ void Module::run(Voice* voice) {
     noise = patchRam.noise / 127.0;
 
     chorus->setChorus(patchRam.switch1 & 0x60);
+    chorus->setHpf(patchRam.switch2 & 0x18);
 
     if (lfoPhase & 0x4000)
         lfo = 0x1fff - (lfoPhase & 0x3fff);