diff --git a/include/cubescript/cubescript.hh b/include/cubescript/cubescript.hh
index c088302..54060e4 100644
--- a/include/cubescript/cubescript.hh
+++ b/include/cubescript/cubescript.hh
@@ -73,7 +73,6 @@ enum {
     IDENT_FLAG_ARG        = 1 << 6
 };
 
-struct bcode;
 struct internal_state;
 struct thread_state;
 struct ident_impl;
@@ -82,7 +81,7 @@ struct LIBCUBESCRIPT_EXPORT bcode_ref {
     bcode_ref():
         p_code(nullptr)
     {}
-    bcode_ref(bcode *v);
+    bcode_ref(struct bcode *v);
     bcode_ref(bcode_ref const &v);
     bcode_ref(bcode_ref &&v):
         p_code(v.p_code)
@@ -95,15 +94,15 @@ struct LIBCUBESCRIPT_EXPORT bcode_ref {
     bcode_ref &operator=(bcode_ref const &v);
     bcode_ref &operator=(bcode_ref &&v);
 
-    operator bool() const { return p_code != nullptr; }
-    operator bcode *() const { return p_code; }
+    bool empty() const;
+
+    operator bool() const;
+    operator struct bcode *() const;
 
 private:
-    bcode *p_code;
+    struct bcode *p_code;
 };
 
-LIBCUBESCRIPT_EXPORT bool code_is_empty(bcode *code);
-
 struct LIBCUBESCRIPT_EXPORT string_ref {
     friend struct any_value;
     friend struct string_pool;
@@ -165,13 +164,13 @@ struct LIBCUBESCRIPT_EXPORT any_value {
     void set_str(std::string_view val);
     void set_str(string_ref const &val);
     void set_none();
-    void set_code(bcode *val);
+    void set_code(bcode_ref const &val);
     void set_ident(ident *val);
 
     string_ref get_str() const;
     integer_type get_int() const;
     float_type get_float() const;
-    bcode *get_code() const;
+    bcode_ref get_code() const;
     ident *get_ident() const;
     void get_val(any_value &r) const;
 
@@ -181,11 +180,9 @@ struct LIBCUBESCRIPT_EXPORT any_value {
     float_type force_float();
     integer_type force_int();
     std::string_view force_str();
-    bcode *force_code(state &cs);
+    bcode_ref force_code(state &cs);
     ident *force_ident(state &cs);
 
-    bool code_is_empty() const;
-
 private:
     template<typename T>
     struct stor_t {
@@ -440,18 +437,18 @@ struct LIBCUBESCRIPT_EXPORT state {
     void reset_var(std::string_view name);
     void touch_var(std::string_view name);
 
-    void run(bcode *code, any_value &ret);
+    void run(bcode_ref const &code, any_value &ret);
     void run(std::string_view code, any_value &ret);
     void run(std::string_view code, any_value &ret, std::string_view source);
     void run(ident *id, std::span<any_value> args, any_value &ret);
 
-    any_value run(bcode *code);
+    any_value run(bcode_ref const &code);
     any_value run(std::string_view code);
     any_value run(std::string_view code, std::string_view source);
     any_value run(ident *id, std::span<any_value> args);
 
-    loop_state run_loop(bcode *code, any_value &ret);
-    loop_state run_loop(bcode *code);
+    loop_state run_loop(bcode_ref const &code, any_value &ret);
+    loop_state run_loop(bcode_ref const &code);
 
     bool is_in_loop() const;
 
diff --git a/src/cs_bcode.cc b/src/cs_bcode.cc
index 7312ee2..80a3410 100644
--- a/src/cs_bcode.cc
+++ b/src/cs_bcode.cc
@@ -34,6 +34,21 @@ LIBCUBESCRIPT_EXPORT bcode_ref &bcode_ref::operator=(bcode_ref &&v) {
     return *this;
 }
 
+LIBCUBESCRIPT_EXPORT bool bcode_ref::empty() const {
+    if (!p_code) {
+        return true;
+    }
+    return (*p_code->get_raw() & BC_INST_OP_MASK) == BC_INST_EXIT;
+}
+
+LIBCUBESCRIPT_EXPORT bcode_ref::operator bool() const {
+    return p_code != nullptr;
+}
+
+LIBCUBESCRIPT_EXPORT bcode_ref::operator bcode *() const {
+    return p_code;
+}
+
 /* private funcs */
 
 struct bcode_hdr {
diff --git a/src/cs_state.cc b/src/cs_state.cc
index 175de22..d645c01 100644
--- a/src/cs_state.cc
+++ b/src/cs_state.cc
@@ -126,7 +126,7 @@ state::state(alloc_func func, void *data) {
             res.set_int(1);
         } else {
             for (size_t i = 0; i < args.size(); ++i) {
-                bcode *code = args[i].get_code();
+                auto code = args[i].get_code();
                 if (code) {
                     cs.run(code, res);
                 } else {
@@ -145,7 +145,7 @@ state::state(alloc_func func, void *data) {
             res.set_int(0);
         } else {
             for (size_t i = 0; i < args.size(); ++i) {
-                bcode *code = args[i].get_code();
+                auto code = args[i].get_code();
                 if (code) {
                     cs.run(code, res);
                 } else {
@@ -780,8 +780,9 @@ LIBCUBESCRIPT_EXPORT void state::init_libs(int libs) {
     }
 }
 
-LIBCUBESCRIPT_EXPORT void state::run(bcode *code, any_value &ret) {
-    vm_exec(*p_tstate, reinterpret_cast<std::uint32_t *>(code), ret);
+LIBCUBESCRIPT_EXPORT void state::run(bcode_ref const &code, any_value &ret) {
+    bcode *p = code;
+    vm_exec(*p_tstate, reinterpret_cast<std::uint32_t *>(p), ret);
 }
 
 static void do_run(
@@ -897,7 +898,7 @@ LIBCUBESCRIPT_EXPORT void state::run(
     }
 }
 
-LIBCUBESCRIPT_EXPORT any_value state::run(bcode *code) {
+LIBCUBESCRIPT_EXPORT any_value state::run(bcode_ref const &code) {
     any_value ret{*this};
     run(code, ret);
     return ret;
@@ -925,7 +926,9 @@ LIBCUBESCRIPT_EXPORT any_value state::run(
     return ret;
 }
 
-LIBCUBESCRIPT_EXPORT loop_state state::run_loop(bcode *code, any_value &ret) {
+LIBCUBESCRIPT_EXPORT loop_state state::run_loop(
+    bcode_ref const &code, any_value &ret
+) {
     ++p_tstate->loop_level;
     try {
         run(code, ret);
@@ -942,7 +945,7 @@ LIBCUBESCRIPT_EXPORT loop_state state::run_loop(bcode *code, any_value &ret) {
     return loop_state::NORMAL;
 }
 
-LIBCUBESCRIPT_EXPORT loop_state state::run_loop(bcode *code) {
+LIBCUBESCRIPT_EXPORT loop_state state::run_loop(bcode_ref const &code) {
     any_value ret{*this};
     return run_loop(code, ret);
 }
diff --git a/src/cs_val.cc b/src/cs_val.cc
index f5dab58..32823c2 100644
--- a/src/cs_val.cc
+++ b/src/cs_val.cc
@@ -168,11 +168,12 @@ void any_value::set_none() {
     p_type = value_type::NONE;
 }
 
-void any_value::set_code(bcode *val) {
+void any_value::set_code(bcode_ref const &val) {
+    bcode *p = val;
     csv_cleanup(p_type, &p_stor);
     p_type = value_type::CODE;
-    bcode_addref(val->get_raw());
-    csv_get<bcode *>(&p_stor) = val;
+    bcode_addref(p->get_raw());
+    csv_get<bcode *>(&p_stor) = p;
 }
 
 void any_value::set_ident(ident *val) {
@@ -250,10 +251,10 @@ std::string_view any_value::force_str() {
     ));
 }
 
-bcode *any_value::force_code(state &cs) {
+bcode_ref any_value::force_code(state &cs) {
     switch (get_type()) {
         case value_type::CODE:
-            return csv_get<bcode *>(&p_stor);
+            return bcode_ref{csv_get<bcode *>(&p_stor)};
         default:
             break;
     }
@@ -265,7 +266,7 @@ bcode *any_value::force_code(state &cs) {
     std::memcpy(cbuf, gs.code.data(), gs.code.size() * sizeof(std::uint32_t));
     auto *bc = reinterpret_cast<bcode *>(cbuf + 1);
     set_code(bc);
-    return bc;
+    return bcode_ref{bc};
 }
 
 ident *any_value::force_ident(state &cs) {
@@ -312,11 +313,11 @@ float_type any_value::get_float() const {
     return 0.0f;
 }
 
-bcode *any_value::get_code() const {
+bcode_ref any_value::get_code() const {
     if (get_type() != value_type::CODE) {
-        return nullptr;
+        return bcode_ref{};
     }
-    return csv_get<bcode *>(&p_stor);
+    return bcode_ref{csv_get<bcode *>(&p_stor)};
 }
 
 ident *any_value::get_ident() const {
@@ -365,20 +366,6 @@ void any_value::get_val(any_value &r) const {
     }
 }
 
-LIBCUBESCRIPT_EXPORT bool code_is_empty(bcode *code) {
-    if (!code) {
-        return true;
-    }
-    return (*code->get_raw() & BC_INST_OP_MASK) == BC_INST_EXIT;
-}
-
-bool any_value::code_is_empty() const {
-    if (get_type() != value_type::CODE) {
-        return true;
-    }
-    return cubescript::code_is_empty(csv_get<bcode *>(&p_stor));
-}
-
 bool any_value::get_bool() const {
     switch (get_type()) {
         case value_type::FLOAT:
diff --git a/src/lib_base.cc b/src/lib_base.cc
index 72fbe11..ee55e3e 100644
--- a/src/lib_base.cc
+++ b/src/lib_base.cc
@@ -9,7 +9,7 @@ namespace cubescript {
 
 static inline void do_loop(
     state &cs, ident &id, integer_type offset, integer_type n, integer_type step,
-    bcode *cond, bcode *body
+    bcode_ref &&cond, bcode_ref &&body
 ) {
     if (n <= 0) {
         return;
@@ -34,7 +34,7 @@ static inline void do_loop(
 
 static inline void do_loop_conc(
     state &cs, any_value &res, ident &id, integer_type offset, integer_type n,
-    integer_type step, bcode *body, bool space
+    integer_type step, bcode_ref &&body, bool space
 ) {
     if (n <= 0) {
         return;
@@ -228,7 +228,8 @@ void init_lib_base(state &gcs) {
     });
 
     gcs.new_command("while", "ee", [](auto &cs, auto args, auto &) {
-        bcode *cond = args[0].get_code(), *body = args[1].get_code();
+        auto cond = args[0].get_code();
+        auto body = args[1].get_code();
         while (cs.run(cond).get_bool()) {
             switch (cs.run_loop(body)) {
                 case loop_state::BREAK:
diff --git a/src/lib_list.cc b/src/lib_list.cc
index 947eacb..9a5f47c 100644
--- a/src/lib_list.cc
+++ b/src/lib_list.cc
@@ -74,7 +74,7 @@ static inline void list_assoc(
 
 static void loop_list_conc(
     state &cs, any_value &res, ident *id, std::string_view list,
-    bcode *body, bool space
+    bcode_ref &&body, bool space
 ) {
     if (alias_stack st{cs, id}; st) {
         any_value idv{cs};
@@ -519,7 +519,7 @@ struct ListSortItem {
 struct ListSortFun {
     state &cs;
     alias_stack &xst, &yst;
-    bcode *body;
+    bcode_ref const *body;
 
     bool operator()(ListSortItem const &xval, ListSortItem const &yval) {
         any_value v{cs};
@@ -527,13 +527,13 @@ struct ListSortFun {
         xst.set(std::move(v));
         v.set_str(yval.str);
         yst.set(std::move(v));
-        return cs.run(body).get_bool();
+        return cs.run(*body).get_bool();
     }
 };
 
 static void list_sort(
     state &cs, any_value &res, std::string_view list,
-    ident *x, ident *y, bcode *body, bcode *unique
+    ident *x, ident *y, bcode_ref &&body, bcode_ref &&unique
 ) {
     if (x == y) {
         return;
@@ -561,10 +561,10 @@ static void list_sort(
     size_t totaluniq = total;
     size_t nuniq = items.size();
     if (body) {
-        ListSortFun f = { cs, xst, yst, body };
+        ListSortFun f = { cs, xst, yst, &body };
         std::sort(items.buf.begin(), items.buf.end(), f);
-        if (!code_is_empty(unique)) {
-            f.body = unique;
+        if (!unique.empty()) {
+            f.body = &unique;
             totaluniq = items[0].quote.size();
             nuniq = 1;
             for (size_t i = 1; i < items.size(); i++) {
@@ -578,7 +578,7 @@ static void list_sort(
             }
         }
     } else {
-        ListSortFun f = { cs, xst, yst, unique };
+        ListSortFun f = { cs, xst, yst, &unique };
         totaluniq = items[0].quote.size();
         nuniq = 1;
         for (size_t i = 1; i < items.size(); i++) {