diff --git a/src/cs_gen.cc b/src/cs_gen.cc
index 277bfb4..fb18a84 100644
--- a/src/cs_gen.cc
+++ b/src/cs_gen.cc
@@ -118,6 +118,30 @@ void gen_state::gen_val(
     }
 }
 
+void gen_state::gen_main_null() {
+    code.reserve(code.size() + 4);
+    code.push_back(BC_INST_START);
+    gen_val_null();
+    code.push_back(BC_INST_RESULT);
+    code.push_back(BC_INST_EXIT);
+}
+
+void gen_state::gen_main_integer(integer_type v) {
+    code.reserve(code.size() + bc_store_size<integer_type> + 3);
+    code.push_back(BC_INST_START);
+    gen_val_integer(v);
+    code.push_back(BC_INST_RESULT);
+    code.push_back(BC_INST_EXIT);
+}
+
+void gen_state::gen_main_float(float_type v) {
+    code.reserve(code.size() + bc_store_size<float_type> + 3);
+    code.push_back(BC_INST_START);
+    gen_val_float(v);
+    code.push_back(BC_INST_RESULT);
+    code.push_back(BC_INST_EXIT);
+}
+
 void gen_state::gen_block() {
     code.push_back(BC_INST_EMPTY);
 }
diff --git a/src/cs_gen.hh b/src/cs_gen.hh
index 0d7fdcd..72aec86 100644
--- a/src/cs_gen.hh
+++ b/src/cs_gen.hh
@@ -40,6 +40,10 @@ struct gen_state {
         std::size_t line = 0
     );
 
+    void gen_main_null();
+    void gen_main_integer(integer_type v);
+    void gen_main_float(float_type v);
+
     void gen_block();
     std::pair<std::size_t, std::string_view> gen_block(
         std::string_view v, std::size_t line,
diff --git a/src/cs_vm.cc b/src/cs_vm.cc
index 11e160b..bb8b45c 100644
--- a/src/cs_vm.cc
+++ b/src/cs_vm.cc
@@ -691,18 +691,10 @@ std::uint32_t *vm_exec(
                 gen_state gs{ts};
                 switch (arg.get_type()) {
                     case value_type::INTEGER:
-                        gs.code.reserve(8);
-                        gs.code.push_back(BC_INST_START);
-                        gs.gen_val_integer(arg.get_integer());
-                        gs.code.push_back(BC_INST_RESULT);
-                        gs.code.push_back(BC_INST_EXIT);
+                        gs.gen_main_integer(arg.get_integer());
                         break;
                     case value_type::FLOAT:
-                        gs.code.reserve(8);
-                        gs.code.push_back(BC_INST_START);
-                        gs.gen_val_float(arg.get_float());
-                        gs.code.push_back(BC_INST_RESULT);
-                        gs.code.push_back(BC_INST_EXIT);
+                        gs.gen_main_float(arg.get_float());
                         break;
                     case value_type::STRING: {
                         parser_state ps{ts, gs};
@@ -712,11 +704,7 @@ std::uint32_t *vm_exec(
                         break;
                     }
                     default:
-                        gs.code.reserve(8);
-                        gs.code.push_back(BC_INST_START);
-                        gs.gen_val_null();
-                        gs.code.push_back(BC_INST_RESULT);
-                        gs.code.push_back(BC_INST_EXIT);
+                        gs.gen_main_null();
                         break;
                 }
                 std::uint32_t *cbuf = bcode_alloc(ts.istate, gs.code.size());