diff --git a/card.cpp b/card.cpp
index 6c6cf41ad..b980f773a 100644
--- a/card.cpp
+++ b/card.cpp
@@ -133,6 +133,11 @@ bool card::card_operation_sort(card* c1, card* c2) {
 			return c1->current.sequence < c2->current.sequence;
 	}
 }
+bool card::check_card_setcode(uint32 code, uint32 value) {
+	card_data dat;
+	::read_card(code, &dat);
+	return dat.is_setcode(value);
+}
 void card::attacker_map::addcard(card* pcard) {
 	auto fid = pcard ? pcard->fieldid_r : 0;
 	auto pr = emplace(fid, std::make_pair(pcard, 0));
@@ -488,11 +493,6 @@ inline bool check_setcode(uint16_t setcode, uint32 value) {
 	uint32 setsubtype = value & 0xf000U;
 	return (setcode & 0x0fffU) == settype && (setcode & 0xf000U & setsubtype) == setsubtype;
 }
-bool card::check_card_setcode(uint32 code, uint32 value) {
-	card_data dat;
-	::read_card(code, &dat);
-	return dat.is_setcode(value);
-}
 int32 card::is_set_card(uint32 set_code) {
 	uint32 code1 = get_code();
 	card_data dat1;
diff --git a/card.h b/card.h
index 0f65a9237..100b39f2c 100644
--- a/card.h
+++ b/card.h
@@ -219,6 +219,7 @@ class card {
 	explicit card(duel* pd);
 	~card() = default;
 	static bool card_operation_sort(card* c1, card* c2);
+	static bool check_card_setcode(uint32 code, uint32 value);
 	bool is_extra_deck_monster() const { return !!(data.type & TYPES_EXTRA_DECK); }
 
 	int32 get_infos(byte* buf, uint32 query_flag, int32 use_cache = TRUE);
@@ -227,7 +228,6 @@ class card {
 	std::tuple<uint32, uint32> get_original_code_rule() const;
 	uint32 get_code();
 	uint32 get_another_code();
-	static bool check_card_setcode(uint32 code, uint32 value);
 	int32 is_set_card(uint32 set_code);
 	int32 is_origin_set_card(uint32 set_code);
 	int32 is_pre_set_card(uint32 set_code);
diff --git a/libduel.cpp b/libduel.cpp
index 9b418c63b..01dff5801 100644
--- a/libduel.cpp
+++ b/libduel.cpp
@@ -1990,7 +1990,7 @@ int32 scriptlib::duel_get_mzone_count(lua_State *L) {
 					used_location[p] |= digit;
 					list_mzone[p].push_back(pcard);
 				} else
-					list_mzone[p].push_back(0);
+					list_mzone[p].push_back(nullptr);
 				digit <<= 1;
 			}
 			used_location[p] |= pduel->game_field->player[p].used_location & 0xff00;
@@ -2049,7 +2049,7 @@ int32 scriptlib::duel_get_location_count_fromex(lua_State *L) {
 					used_location[p] |= digit;
 					list_mzone[p].push_back(pcard);
 				} else
-					list_mzone[p].push_back(0);
+					list_mzone[p].push_back(nullptr);
 				digit <<= 1;
 			}
 			used_location[p] |= pduel->game_field->player[p].used_location & 0xff00;
diff --git a/operations.cpp b/operations.cpp
index 30a1137ed..2dbbbc856 100644
--- a/operations.cpp
+++ b/operations.cpp
@@ -641,7 +641,7 @@ int32 field::pay_lp_cost(uint32 step, uint8 playerid, uint32 cost, uint32 must_p
 		core.select_effects.clear();
 		if(val <= player[playerid].lp) {
 			core.select_options.push_back(11);
-			core.select_effects.push_back(0);
+			core.select_effects.push_back(nullptr);
 		}
 		if(must_pay) {
 			if(core.select_options.size() == 0)
@@ -786,7 +786,7 @@ int32 field::remove_overlay_card(uint16 step, uint32 reason, card* pcard, uint8
 		core.select_effects.clear();
 		if((pcard && (int32)pcard->xyz_materials.size() >= min) || (!pcard && get_overlay_count(rplayer, s, o) >= min)) {
 			core.select_options.push_back(12);
-			core.select_effects.push_back(0);
+			core.select_effects.push_back(nullptr);
 		}
 		auto pr = effects.continuous_effect.equal_range(EFFECT_OVERLAY_REMOVE_REPLACE);
 		tevent e;
@@ -1529,7 +1529,7 @@ int32 field::summon(uint16 step, uint8 sumplayer, card* target, effect* proc, ui
 		core.select_effects.clear();
 		core.select_options.clear();
 		if(ignore_count || core.summon_count[sumplayer] < get_summon_count_limit(sumplayer)) {
-			core.select_effects.push_back(0);
+			core.select_effects.push_back(nullptr);
 			core.select_options.push_back(1);
 		}
 		if(!ignore_count && !core.extra_summon[sumplayer]) {
@@ -2104,7 +2104,7 @@ int32 field::mset(uint16 step, uint8 setplayer, card* target, effect* proc, uint
 			core.select_effects.clear();
 			core.select_options.clear();
 			if(res > 0) {
-				core.select_effects.push_back(0);
+				core.select_effects.push_back(nullptr);
 				core.select_options.push_back(1);
 			}
 			for(int32 i = 0; i < eset.size(); ++i) {
@@ -2129,7 +2129,7 @@ int32 field::mset(uint16 step, uint8 setplayer, card* target, effect* proc, uint
 		core.select_effects.clear();
 		core.select_options.clear();
 		if(ignore_count || core.summon_count[setplayer] < get_summon_count_limit(setplayer)) {
-			core.select_effects.push_back(0);
+			core.select_effects.push_back(nullptr);
 			core.select_options.push_back(1);
 		}
 		if(!ignore_count && !core.extra_summon[setplayer]) {