diff --git a/include/pocketpy/interpreter/vm.h b/include/pocketpy/interpreter/vm.h
index 0e2ecc72..678ce84f 100644
--- a/include/pocketpy/interpreter/vm.h
+++ b/include/pocketpy/interpreter/vm.h
@@ -99,6 +99,7 @@ int pk_arrayeq(py_TValue* lhs, int lhs_length, py_TValue* rhs, int rhs_length);
 /// The result is stored in `self->last_retval`.
 /// The stack remains unchanged.
 bool pk_stack_binaryop(pk_VM* self, py_Name op, py_Name rop);
+void pk_print_stack(pk_VM* self, Frame* frame, Bytecode byte);
 
 // type registration
 void pk_object__register();
diff --git a/src/interpreter/ceval.c b/src/interpreter/ceval.c
index 1f5951cc..6671ae4a 100644
--- a/src/interpreter/ceval.c
+++ b/src/interpreter/ceval.c
@@ -83,55 +83,7 @@ pk_FrameResult pk_VM__run_top_frame(pk_VM* self) {
     __NEXT_STEP:
         byte = *frame->ip;
 
-#if 1
-        c11_sbuf buf;
-        c11_sbuf__ctor(&buf);
-        for(py_Ref p = self->stack.begin; p != SP(); p++) {
-            switch(p->type) {
-                case 0: c11_sbuf__write_cstr(&buf, "nil"); break;
-                case tp_int: c11_sbuf__write_i64(&buf, p->_i64); break;
-                case tp_float: c11_sbuf__write_f64(&buf, p->_f64, -1); break;
-                case tp_bool: c11_sbuf__write_cstr(&buf, p->_bool ? "True" : "False"); break;
-                case tp_none_type: c11_sbuf__write_cstr(&buf, "None"); break;
-                case tp_list: {
-                    pk_sprintf(&buf, "list(%d)", py_list__len(p));
-                    break;
-                }
-                case tp_tuple: {
-                    pk_sprintf(&buf, "tuple(%d)", py_tuple__len(p));
-                    break;
-                }
-                case tp_function: {
-                    Function* ud = py_touserdata(p);
-                    c11_sbuf__write_cstr(&buf, ud->decl->code.name->data);
-                    c11_sbuf__write_cstr(&buf, "()");
-                    break;
-                }
-                case tp_type: {
-                    pk_sprintf(&buf, "<class '%t'>", py_totype(p));
-                    break;
-                }
-                case tp_str: {
-                    int size;
-                    const char* data = py_tostrn(p, &size);
-                    pk_sprintf(&buf, "%q", (c11_sv){data, size});
-                    break;
-                }
-                default: {
-                    pk_sprintf(&buf, "(%t)", p->type);
-                    break;
-                }
-            }
-            if(p != TOP()) c11_sbuf__write_cstr(&buf, ", ");
-        }
-        c11_string* stack_str = c11_sbuf__submit(&buf);
-        printf("L%-3d: %-25s %-6d [%s]\n",
-               Frame__lineno(frame),
-               pk_opname(byte.op),
-               byte.arg,
-               stack_str->data);
-        c11_string__delete(stack_str);
-#endif
+        pk_print_stack(self, frame, byte);
 
         switch((Opcode)byte.op) {
             case OP_NO_OP: DISPATCH();
diff --git a/src/interpreter/vm.c b/src/interpreter/vm.c
index 31e4635b..739db762 100644
--- a/src/interpreter/vm.c
+++ b/src/interpreter/vm.c
@@ -334,6 +334,8 @@ bool __prepare_py_call(py_TValue* buffer,
 }
 
 pk_FrameResult pk_VM__vectorcall(pk_VM* self, uint16_t argc, uint16_t kwargc, bool opcall) {
+    pk_print_stack(self, self->top_frame, (Bytecode){});
+
     py_Ref p1 = self->stack.sp - kwargc * 2;
     py_Ref p0 = p1 - argc - 2;
     // [callable, <self>, args..., kwargs...]
@@ -458,7 +460,6 @@ pk_FrameResult pk_VM__vectorcall(pk_VM* self, uint16_t argc, uint16_t kwargc, bo
         *self->stack.sp++ = *p0;     // push cls
         memcpy(self->stack.sp, argv, span * sizeof(py_TValue));
         self->stack.sp += span;
-
         // [new_f, cls, args..., kwargs...]
         pk_FrameResult res = pk_VM__vectorcall(self, argc, kwargc, false);
         if(res == RES_ERROR) return RES_ERROR;
@@ -522,3 +523,56 @@ void pk_ManagedHeap__mark(pk_ManagedHeap* self) {
     // vm->__stack_gc_mark(vm->s_data.begin(), vm->s_data.end());
     // if(self->_gc_marker_ex) self->_gc_marker_ex((pkpy_VM*)vm);
 }
+
+void pk_print_stack(pk_VM* self, Frame* frame, Bytecode byte) {
+    return;
+    py_TValue* sp = self->stack.sp;
+    c11_sbuf buf;
+    c11_sbuf__ctor(&buf);
+    for(py_Ref p = self->stack.begin; p != sp; p++) {
+        switch(p->type) {
+            case 0: c11_sbuf__write_cstr(&buf, "nil"); break;
+            case tp_int: c11_sbuf__write_i64(&buf, p->_i64); break;
+            case tp_float: c11_sbuf__write_f64(&buf, p->_f64, -1); break;
+            case tp_bool: c11_sbuf__write_cstr(&buf, p->_bool ? "True" : "False"); break;
+            case tp_none_type: c11_sbuf__write_cstr(&buf, "None"); break;
+            case tp_list: {
+                pk_sprintf(&buf, "list(%d)", py_list__len(p));
+                break;
+            }
+            case tp_tuple: {
+                pk_sprintf(&buf, "tuple(%d)", py_tuple__len(p));
+                break;
+            }
+            case tp_function: {
+                Function* ud = py_touserdata(p);
+                c11_sbuf__write_cstr(&buf, ud->decl->code.name->data);
+                c11_sbuf__write_cstr(&buf, "()");
+                break;
+            }
+            case tp_type: {
+                pk_sprintf(&buf, "<class '%t'>", py_totype(p));
+                break;
+            }
+            case tp_str: {
+                int size;
+                const char* data = py_tostrn(p, &size);
+                pk_sprintf(&buf, "%q", (c11_sv){data, size});
+                break;
+            }
+            default: {
+                pk_sprintf(&buf, "(%t)", p->type);
+                break;
+            }
+        }
+        if(p != &sp[-1]) c11_sbuf__write_cstr(&buf, ", ");
+    }
+    c11_string* stack_str = c11_sbuf__submit(&buf);
+
+    printf("L%-3d: %-25s %-6d [%s]\n",
+           Frame__lineno(frame),
+           pk_opname(byte.op),
+           byte.arg,
+           stack_str->data);
+    c11_string__delete(stack_str);
+}
\ No newline at end of file
diff --git a/src/public/error.c b/src/public/error.c
index 68c5e333..46ce091b 100644
--- a/src/public/error.c
+++ b/src/public/error.c
@@ -35,9 +35,9 @@ bool py_exception(const char* name, const char* fmt, ...) {
     py_Ref message = py_pushtmp();
     py_newstrn(message, res->data, res->size);
     c11_string__delete(res);
+    bool ok = py_tpcall(tp_exception, 1, message);
     py_pop();
 
-    bool ok = py_tpcall(tp_exception, 1, message);
     if(!ok) abort();
     vm->last_exception = *py_retval();
 
diff --git a/src/public/py_list.c b/src/public/py_list.c
index 71546025..7255d396 100644
--- a/src/public/py_list.c
+++ b/src/public/py_list.c
@@ -110,10 +110,11 @@ static bool _py_list__new__(int argc, py_Ref argv) {
             }
             return true;
         }
+        
+        if(!py_iter(py_arg(1))) return false;
 
         py_Ref iter = py_pushtmp();
         py_Ref list = py_pushtmp();
-        if(!py_iter(py_arg(1))) return false;
         *iter = *py_retval();
         py_newlist(list);
         while(true) {