diff --git a/MicroMDAEPiano.ino b/MicroMDAEPiano.ino
index 23c9be8..992b253 100644
--- a/MicroMDAEPiano.ino
+++ b/MicroMDAEPiano.ino
@@ -239,8 +239,10 @@ void setup()
   }
 
   // chorus modulation fixed
+  memset(r_delayline,0,sizeof(short)*CHORUS_DELAY_LENGTH);
+  memset(l_delayline,0,sizeof(short)*CHORUS_DELAY_LENGTH);
   mod_sine1.amplitude(1.0);
-  mod_sine1.frequency(5.0);
+  mod_sine1.frequency(2.0);
   mod_sine1.phase(0);
   // chorus level fixed
   mixer_r.gain(2, 1.0);
diff --git a/effect_modulated_chorus.cpp b/effect_modulated_chorus.cpp
index c5d8e9e..bf25d5e 100644
--- a/effect_modulated_chorus.cpp
+++ b/effect_modulated_chorus.cpp
@@ -132,18 +132,17 @@ void AudioModulatedEffectChorus::update(void)
       // linear interpolation
       x1 = int(mod_idx);
       y1 = *(block->data + x1);
-      if (x1 + 1 > delay_length)
+      if (x1 + 1 >= delay_length)
       {
         x2 = 0;
-        y2 = *block->data;
+        y2 = *bp;
       }
       else
       {
         x2 = x1 + 1;
-        y2 = *(block->data + x2);
+        y2 = *bp + x2;
       }
       *bp = (*bp >> 1) + (int((float(y2 - y1) / (x2 - x1) * (mod_idx - x1) + y1) + 0.5) >> 1); // mix original signal 1:1 with modulated signal
-
       bp++;
       mp++;
       l_circ_idx++;