diff --git a/src/codegen.c b/src/codegen.c
index 67b2f09d..812dd357 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -709,6 +709,7 @@ print_irep(pic_state *pic, struct pic_irep *irep)
   printf("## irep %p\n", irep);
   printf("[clen = %zd, ccapa = %zd, argc = %d, localc = %d]\n", irep->clen, irep->ccapa, irep->argc, irep->localc);
   for (i = 0; i < irep->clen; ++i) {
+    printf("[%2d] ", irep->code[i].insn);
     switch (irep->code[i].insn) {
     case OP_POP:
       puts("OP_POP");
diff --git a/src/expand.c b/src/expand.c
index ed498362..5095ddee 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -44,6 +44,12 @@ expand(pic_state *pic, pic_value obj, struct syntactic_env *env)
 {
   int ai = pic_gc_arena_preserve(pic);
 
+#if DEBUG
+  printf("expanding...");
+  pic_debug(pic, obj);
+  puts("");
+#endif
+
   switch (pic_type(obj)) {
   case PIC_TT_SYMBOL: {
     return obj;
@@ -147,14 +153,21 @@ pic_expand(pic_state *pic, pic_value obj)
 
   env.tbl = pic->global_tbl;
 
+#if DEBUG
+  puts("before expand:");
+  pic_debug(pic, obj);
+  puts("");
+#endif
+
   v = expand(pic, obj, &env);
 
   pic_gc_arena_restore(pic, ai);
   pic_gc_protect(pic, v);
 
 #if DEBUG
-  puts("expanded:");
+  puts("after expand:");
   pic_debug(pic, v);
+  puts("");
 #endif
 
   return v;
diff --git a/src/vm.c b/src/vm.c
index a4ec93f4..c52eb707 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -157,9 +157,15 @@ pic_get_args(pic_state *pic, const char *format, ...)
   return i;
 }
 
+#if VM_DEBUG
+# define OPCODE_EXEC_HOOK printf("OP = %d\n", c.insn)
+#else
+# define OPCODE_EXEC_HOOK ((void)0)
+#endif
+
 #if PIC_DIRECT_THREADED_VM
 # define VM_LOOP JUMP;
-# define CASE(x) L_##x:
+# define CASE(x) L_##x: OPCODE_EXEC_HOOK;
 # define NEXT c = *++pc; JUMP;
 # define JUMP c = *pc; goto *oplabels[pc->insn];
 # define VM_LOOP_END
@@ -207,6 +213,19 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value argv)
 
   argc = pic_length(pic, argv) + 1;
 
+#if VM_DEBUG
+  puts("== booting VM...");
+  printf("  proc = ");
+  pic_debug(pic, pic_obj_value(proc));
+  puts("");
+  printf("  argv = ");
+  pic_debug(pic, argv);
+  puts("");
+  printf("  irep = ");
+  print_irep(pic, proc->u.irep);
+  puts("\nLet's go!");
+#endif
+
   PUSH(pic_obj_value(proc));
   for (i = 1; i < argc; ++i) {
     PUSH(pic_car(pic, argv));