diff --git a/libs/core/control.cpp b/libs/core/control.cpp
index 62a2b4c7..f8e740e2 100644
--- a/libs/core/control.cpp
+++ b/libs/core/control.cpp
@@ -307,7 +307,7 @@ namespace control {
     * Informs simulator/runtime of a MIDI message
     * Internal function to support the simulator.
     */
-    //% part=midioutput block
+    //% part=midioutput blockHidden=1
     void __midiSend(Buffer buffer) {
         // this is a stub to support the simulator
     }
diff --git a/libs/core/shims.d.ts b/libs/core/shims.d.ts
index 6cd16da1..87c08f23 100644
--- a/libs/core/shims.d.ts
+++ b/libs/core/shims.d.ts
@@ -437,7 +437,7 @@ declare namespace control {
      * Informs simulator/runtime of a MIDI message
      * Internal function to support the simulator.
      */
-    //% part=midioutput block shim=control::__midiSend
+    //% part=midioutput blockHidden=1 shim=control::__midiSend
     function __midiSend(buffer: Buffer): void;
 }