diff --git a/engine.c b/engine.c
index 0f02955..2e8ef48 100644
--- a/engine.c
+++ b/engine.c
@@ -40,6 +40,8 @@ static int process_callback(jack_nframes_t nframes, void *arg) {
     transport_process(engine->transport, nframes, midi_clock_buf, midi_out_buf);
     
     // Process control channel MIDI input (clip triggers)
+    int event_index;
+    jack_midi_event_t midi_event;
     event_index = 0;
     while (jack_midi_event_get(&midi_event, midi_in_buf, event_index) == 0) {
         event_index++;