diff --git a/engine.c b/engine.c
index 2e8ef48..7d2110b 100644
--- a/engine.c
+++ b/engine.c
@@ -201,14 +201,18 @@ void queue_trigger(Engine *engine, int clip_index, bool is_scene, jack_nframes_t
         engine->queued_triggers = qt;
     } else {
         QueuedTrigger *last = engine->queued_triggers;
-        while (last->next) last = last->next;
-        last->next = qt;
+        while (last && last->next) last = last->next;  // FIX: add null check for last
+        if (last) {  // ADD THIS
+            last->next = qt;
+        } else {
+            engine->queued_triggers = qt;  // Fallback
+        }
     }
 }
 
 // Process queued triggers at quantization boundaries
 static void process_queued_triggers(Engine *engine, jack_nframes_t nframes) {
-    if (!engine->queued_triggers) return;
+    if (!engine || !engine->queued_triggers) return;  // FIX: add engine null check
     TransportState transport_state = (TransportState)atomic_load(&engine->transport->state_atomic);
     if (transport_state != TRANSPORT_PLAYING) return;
     
@@ -281,6 +285,7 @@ void engine_process_commands(Engine *engine) {
             case CMD_TRIGGER_CLIP: {
                 if (cmd.index < 0 || cmd.index >= MAX_CLIPS) break;
                 Clip *clip = &engine->clips[cmd.index];
+                if (!clip->buffer) break;  // ADD THIS - prevent segfault on freed buffer
                 
                 // Record undo action
                 UndoAction action;
@@ -503,10 +508,13 @@ void engine_undo(Engine *engine) {
     switch (action->type) {
         case ACTION_TRIGGER_CLIP: {
             int clip_idx = action->index;
-            engine->clips[clip_idx].state = action->previous_state;
-            engine->clips[clip_idx].buffer_size = action->previous_buffer_size;
-            engine->clips[clip_idx].write_position = action->previous_write_position;
-            engine->clips[clip_idx].read_position = action->previous_read_position;
+            if (clip_idx < 0 || clip_idx >= MAX_CLIPS) break;
+            Clip *clip = &engine->clips[clip_idx];
+            if (!clip->buffer) break;  // ADD THIS
+            clip->state = action->previous_state;
+            clip->buffer_size = action->previous_buffer_size;
+            clip->write_position = action->previous_write_position;
+            clip->read_position = action->previous_read_position;
             break;
         }
             
@@ -574,8 +582,10 @@ void engine_redo(Engine *engine) {
     switch (action->type) {
         case ACTION_TRIGGER_CLIP: {
             int clip_idx = action->index;
-            // Re-apply the trigger by directly manipulating state
+            if (clip_idx < 0 || clip_idx >= MAX_CLIPS) break;
             Clip *clip = &engine->clips[clip_idx];
+            if (!clip->buffer) break;  // ADD THIS
+            // Re-apply the trigger by directly manipulating state
             switch (clip->state) {
                 case CLIP_EMPTY:
                     clip->state = CLIP_RECORDING;
@@ -699,6 +709,7 @@ int engine_init(Engine *engine, const char *client_name) {
         // Cleanup on allocation failure
         for (int j = 0; j < MAX_CLIPS; j++) {
             free(engine->clips[j].buffer);
+            engine->clips[j].buffer = NULL;  // ADD THIS
         }
         return -1;
     }
@@ -712,7 +723,10 @@ int engine_init(Engine *engine, const char *client_name) {
             // Cleanup on allocation failure
             for (int j = 0; j < i; j++) {
                 free(engine->clips[j].buffer);
+                engine->clips[j].buffer = NULL;  // ADD THIS
             }
+            free(engine->transport);
+            engine->transport = NULL;  // ADD THIS
             return -1;
         }
         engine->clips[i].buffer_size = 0;
diff --git a/transport.c b/transport.c
index e047d4d..f49dd9e 100644
--- a/transport.c
+++ b/transport.c
@@ -112,7 +112,7 @@ double transport_get_bpm(Transport *transport) {
 
 int transport_process(Transport *transport, jack_nframes_t nframes,
                       void *midi_clock_in_buf, void *midi_clock_out_buf) {
-    if (!transport) return 0;
+    if (!transport) return -1;  // ADD THIS
     
     int clock_ticks_generated = 0;