diff --git a/src/App.vue b/src/App.vue
index 55630292..cb489218 100644
--- a/src/App.vue
+++ b/src/App.vue
@@ -85,6 +85,12 @@ function midiNoteOn(index: number, rawAttack?: number, channel?: number) {
   }
 
   let frequency = scale.frequencies[index]
+
+  // if index out of range calculate frequency directly
+  if (index < 0 || index > 127) {
+    frequency = scale.getFrequency(index)
+  }
+
   if (!midi.velocityOn) {
     rawAttack = 80
   }