diff --git a/conf/msg_conf/map_msg.conf b/conf/msg_conf/map_msg.conf
index 81428aaa5e..8e2b5b1478 100644
--- a/conf/msg_conf/map_msg.conf
+++ b/conf/msg_conf/map_msg.conf
@@ -839,7 +839,11 @@
 784: Baby Star Emperor
 785: Baby Soul Reaper
 
-//786-899 free
+// Guild Storage Expansion Skill
+786: The guild does not have a guild storage.
+787: You do not have permission to use the guild storage.
+
+//788-899 free
 
 //------------------------------------
 // More atcommands message
diff --git a/db/guild_skill_tree.txt b/db/guild_skill_tree.txt
index 8572244aad..569d490ee0 100644
--- a/db/guild_skill_tree.txt
+++ b/db/guild_skill_tree.txt
@@ -27,3 +27,4 @@
 10012,1,10011,1,0,0,0,0,0,0,0,0	//GD_RESTORE#Restoration#
 10013,1,10000,1,10002,1,10004,5,10010,1,10011,1	//GD_EMERGENCYCALL#Urgent Call#
 10014,1,0,0,0,0,0,0,0,0,0,0	//GD_DEVELOPMENT#Permanent Development#
+10016,5,0,0,0,0,0,0,0,0,0,0	//GD_GUILD_STORAGE#Guild Storage Expansion#
diff --git a/db/pre-re/skill_db.txt b/db/pre-re/skill_db.txt
index 84956a6018..80a3f71abc 100644
--- a/db/pre-re/skill_db.txt
+++ b/db/pre-re/skill_db.txt
@@ -1553,3 +1553,4 @@
 10013,0,0,4,0,0x3,0,1,0,yes,0,0x10,0,none,0,0x40,	GD_EMERGENCYCALL,Urgent Call
 10014,0,0,0,0,0,0,1,0,no,0,0x10,0,none,0,0x0,	GD_DEVELOPMENT,Permanent Development
 10015,0,0,4,0,0x3,0,3,0,yes,0,0x10,0,none,0,0x40,	GD_ITEMEMERGENCYCALL,Item Emergency Call
+10016,0,0,0,0,0,0,5,0,no,0,0x10,0,none,0,0x0,	GD_GUILD_STORAGE,Guild Storage Expansion
diff --git a/db/re/skill_db.txt b/db/re/skill_db.txt
index 857cb6db77..654c3648e4 100644
--- a/db/re/skill_db.txt
+++ b/db/re/skill_db.txt
@@ -1611,3 +1611,4 @@
 10013,0,0,4,0,0x3,0,1,0,yes,0,0x10,0,none,0,0x40,	GD_EMERGENCYCALL,Urgent Call
 10014,0,0,0,0,0,0,1,0,no,0,0x10,0,none,0,0x0,	GD_DEVELOPMENT,Permanent Development
 10015,0,0,4,0,0x3,0,3,0,yes,0,0x10,0,none,0,0x40,	GD_ITEMEMERGENCYCALL,Item Emergency Call
+10016,0,0,0,0,0,0,5,0,no,0,0x10,0,none,0,0x0,	GD_GUILD_STORAGE,Guild Storage Expansion
diff --git a/doc/script_commands.txt b/doc/script_commands.txt
index 9f61c38855..fed9570442 100644
--- a/doc/script_commands.txt
+++ b/doc/script_commands.txt
@@ -5416,12 +5416,15 @@ This will open the Auction window on the client connected to the invoking charac
 
 This function works the same as 'openstorage' but will open a guild storage
 window instead for the guild storage of the guild the invoking character belongs
-to. This is a function because it returns a value - 0 if the guild storage was
-opened successfully and 1 if it wasn't. (Notice, it's a ZERO upon success.)
-Since guild storage is only accessible to one character at one time, it may fail
-if another character is accessing the guild storage at the same time.
+to.
 
-This will also fail and return 2 if the character does not belong to any guild.
+Return values:
+ GSTORAGE_OPEN - Successfully opened.
+ GSTORAGE_STORAGE_ALREADY_OPEN - Player storage is already open.
+ GSTORAGE_ALREADY_OPEN - Guild storage is already open.
+ GSTORAGE_NO_GUILD - Player is not in a guild.
+ GSTORAGE_NO_STORAGE - Guild hasn't invested in the Guild Storage Expansion skill (only if OFFICIAL_GUILD_STORAGE is enabled).
+ GSTORAGE_NO_PERMISSION - Player doesn't have permission to use the guild storage.
 
 ---------------------------------------
 
diff --git a/sql-files/main.sql b/sql-files/main.sql
index d8c0f00cd7..50f9bfbb17 100644
--- a/sql-files/main.sql
+++ b/sql-files/main.sql
@@ -525,7 +525,7 @@ CREATE TABLE IF NOT EXISTS `guild_position` (
   `guild_id` int(9) unsigned NOT NULL default '0',
   `position` tinyint(6) unsigned NOT NULL default '0',
   `name` varchar(24) NOT NULL default '',
-  `mode` tinyint(11) unsigned NOT NULL default '0',
+  `mode` smallint(11) unsigned NOT NULL default '0',
   `exp_mode` tinyint(11) unsigned NOT NULL default '0',
   PRIMARY KEY  (`guild_id`,`position`)
 ) ENGINE=MyISAM;
diff --git a/sql-files/upgrades/upgrade_20180623.sql b/sql-files/upgrades/upgrade_20180623.sql
new file mode 100644
index 0000000000..bf8c47fefc
--- /dev/null
+++ b/sql-files/upgrades/upgrade_20180623.sql
@@ -0,0 +1 @@
+ALTER TABLE `guild_position` MODIFY COLUMN `mode` smallint(11) unsigned NOT NULL default '0';
diff --git a/src/char/char.cpp b/src/char/char.cpp
index af1ade357d..80385e3484 100644
--- a/src/char/char.cpp
+++ b/src/char/char.cpp
@@ -738,7 +738,7 @@ int char_memitemdata_to_sql(const struct item items[], int max, int id, enum sto
 bool char_memitemdata_from_sql(struct s_storage* p, int max, int id, enum storage_type tableswitch, uint8 stor_id) {
 	StringBuf buf;
 	SqlStmt* stmt;
-	int i,j, offset = 0;
+	int i,j, offset = 0, max2;
 	struct item item, *storage;
 	const char *tablename, *selectoption, *printname;
 
@@ -748,24 +748,28 @@ bool char_memitemdata_from_sql(struct s_storage* p, int max, int id, enum storag
 			tablename = schema_config.inventory_db;
 			selectoption = "char_id";
 			storage = p->u.items_inventory;
+			max2 = MAX_INVENTORY;
 			break;
 		case TABLE_CART:
 			printname = "Cart";
 			tablename = schema_config.cart_db;
 			selectoption = "char_id";
 			storage = p->u.items_cart;
+			max2 = MAX_CART;
 			break;
 		case TABLE_STORAGE:
 			printname = "Storage";
 			tablename = inter_premiumStorage_getTableName(stor_id);
 			selectoption = "account_id";
 			storage = p->u.items_storage;
+			max2 = inter_premiumStorage_getMax(p->stor_id);
 			break;
 		case TABLE_GUILD_STORAGE:
 			printname = "Guild Storage";
 			tablename = schema_config.guild_storage_db;
 			selectoption = "guild_id";
 			storage = p->u.items_guild;
+			max2 = inter_guild_storagemax(id);
 			break;
 		default:
 			ShowError("Invalid table name!\n");
@@ -776,7 +780,7 @@ bool char_memitemdata_from_sql(struct s_storage* p, int max, int id, enum storag
 	p->id = id;
 	p->type = tableswitch;
 	p->stor_id = stor_id;
-	p->max_amount = inter_premiumStorage_getMax(p->stor_id);
+	p->max_amount = max2;
 
 	stmt = SqlStmt_Malloc(sql_handle);
 	if (stmt == NULL) {
diff --git a/src/char/int_guild.cpp b/src/char/int_guild.cpp
index d34b746e51..29aa4286cc 100644
--- a/src/char/int_guild.cpp
+++ b/src/char/int_guild.cpp
@@ -46,6 +46,7 @@ int mapif_guild_basicinfochanged(int guild_id,int type,const void *data,int len)
 int mapif_guild_info(int fd,struct guild *g);
 int guild_break_sub(int key,void *data,va_list ap);
 int inter_guild_tosql(struct guild *g,int flag);
+int guild_checkskill(struct guild *g, int id);
 
 int guild_save_timer(int tid, unsigned int tick, int id, intptr_t data)
 {
@@ -526,6 +527,32 @@ struct guild * inter_guild_fromsql(int guild_id)
 	return g;
 }
 
+/**
+ * Get the max storage size of a guild.
+ * @param guild_id: Guild ID to search
+ * @return Guild storage max size
+ */
+uint16 inter_guild_storagemax(int guild_id)
+{
+#ifdef OFFICIAL_GUILD_STORAGE
+	struct guild *g = inter_guild_fromsql(guild_id);
+	uint16 max = 0;
+
+	if (!g) {
+		ShowError("Guild %d not found!\n", guild_id);
+		return 0;
+	}
+
+	max = guild_checkskill(g, GD_GUILD_STORAGE);
+	if (max)
+		max *= 100;
+
+	return max;
+#else
+	return MAX_GUILD_STORAGE;
+#endif
+}
+
 // `guild_castle` (`castle_id`, `guild_id`, `economy`, `defense`, `triggerE`, `triggerD`, `nextTime`, `payTime`, `createTime`, `visibleC`, `visibleG0`, `visibleG1`, `visibleG2`, `visibleG3`, `visibleG4`, `visibleG5`, `visibleG6`, `visibleG7`)
 int inter_guildcastle_tosql(struct guild_castle *gc)
 {
@@ -1164,7 +1191,7 @@ int mapif_parse_CreateGuild(int fd,uint32 account_id,char *name,struct guild_mem
 	g->member[0].modified = GS_MEMBER_MODIFIED;
 
 	// Set default positions
-	g->position[0].mode=0x11;
+	g->position[0].mode = GUILD_PERM_DEFAULT;
 	strcpy(g->position[0].name,"GuildMaster");
 	strcpy(g->position[MAX_GUILDPOSITION-1].name,"Newbie");
 	g->position[0].modified = g->position[MAX_GUILDPOSITION-1].modified = GS_POSITION_MODIFIED;
diff --git a/src/char/int_guild.hpp b/src/char/int_guild.hpp
index 85b45d0fe6..4271090b96 100644
--- a/src/char/int_guild.hpp
+++ b/src/char/int_guild.hpp
@@ -35,5 +35,6 @@ int inter_guild_sex_changed(int guild_id,uint32 account_id,uint32 char_id, short
 int inter_guild_charname_changed(int guild_id,uint32 account_id, uint32 char_id, char *name);
 int inter_guild_CharOnline(uint32 char_id, int guild_id);
 int inter_guild_CharOffline(uint32 char_id, int guild_id);
+uint16 inter_guild_storagemax(int guild_id);
 
 #endif /* _INT_GUILD_HPP_ */
diff --git a/src/char/int_storage.cpp b/src/char/int_storage.cpp
index 0afa72518a..6851062b10 100644
--- a/src/char/int_storage.cpp
+++ b/src/char/int_storage.cpp
@@ -19,18 +19,18 @@
 
 /**
  * Check if storage ID is valid
- * @param id Storage ID
- * @return True:Valid, False:Invalid
- **/
+ * @param id: Storage ID
+ * @return True if success or false on failure
+ */
 bool inter_premiumStorage_exists(uint8 id) {
 	return interserv_config.storages.find(id) != interserv_config.storages.end();
 }
 
 /**
  * Get max storage amount
- * @param id Storage ID
+ * @param id: Storage ID
  * @return Max amount
- **/
+ */
 int inter_premiumStorage_getMax(uint8 id) {
 	if (inter_premiumStorage_exists(id))
 		return interserv_config.storages[id]->max_num;
@@ -39,9 +39,9 @@ int inter_premiumStorage_getMax(uint8 id) {
 
 /**
  * Get table name of storage
- * @param id Storage ID
+ * @param id: Storage ID
  * @return Table name
- **/
+ */
 const char *inter_premiumStorage_getTableName(uint8 id) {
 	if (inter_premiumStorage_exists(id))
 		return interserv_config.storages[id]->table;
@@ -49,10 +49,10 @@ const char *inter_premiumStorage_getTableName(uint8 id) {
 }
 
 /**
-* Get printable name of storage
-* @param id Storage ID
-* @return printable name
-**/
+ * Get printable name of storage
+ * @param id: Storage ID
+ * @return printable name
+ */
 const char *inter_premiumStorage_getPrintableName(uint8 id) {
 	if (inter_premiumStorage_exists(id))
 		return interserv_config.storages[id]->name;
@@ -95,7 +95,7 @@ int cart_tosql(uint32 char_id, struct s_storage* p)
 /**
  * Fetch inventory entries from table
  * @param char_id: Character ID to fetch
- * @param p: Inventory list to save the entries
+ * @param p: Inventory entries
  * @return True if success, False if failed
  */
 bool inventory_fromsql(uint32 char_id, struct s_storage* p)
@@ -106,7 +106,7 @@ bool inventory_fromsql(uint32 char_id, struct s_storage* p)
 /**
  * Fetch cart entries from table
  * @param char_id: Character ID to fetch
- * @param p: Cart list to save the entries
+ * @param p: Cart entries
  * @return True if success, False if failed
  */
 bool cart_fromsql(uint32 char_id, struct s_storage* p)
@@ -116,8 +116,8 @@ bool cart_fromsql(uint32 char_id, struct s_storage* p)
 
 /**
  * Fetch storage entries from table
- * @param char_id: Character ID to fetch
- * @param p: Storage list to save the entries
+ * @param account_id: Account ID to fetch
+ * @param p: Storage entries
  * @param stor_id: Storage ID
  * @return True if success, False if failed
  */
@@ -128,9 +128,9 @@ bool storage_fromsql(uint32 account_id, struct s_storage* p)
 
 /**
  * Save guild_storage data to sql
- * @param guild_id: Character ID to save
- * @param p: Guild Storage list to save the entries
- * @return 0 if success, or error count
+ * @param guild_id: Guild ID to save
+ * @param p: Guild Storage entries
+ * @return True if success, False if failed
  */
 bool guild_storage_tosql(int guild_id, struct s_storage* p)
 {
@@ -140,8 +140,8 @@ bool guild_storage_tosql(int guild_id, struct s_storage* p)
 
 /**
  * Fetch guild_storage entries from table
- * @param char_id: Character ID to fetch
- * @param p: Storage list to save the entries
+ * @param guild_id: Guild ID to fetch
+ * @param p: Guild Storage entries
  * @return True if success, False if failed
  */
 bool guild_storage_fromsql(int guild_id, struct s_storage* p)
@@ -181,6 +181,14 @@ void inter_storage_sql_final(void)
 //---------------------------------------------------------
 // packet from map server
 
+/**
+ * Send guild storage data to the map server
+ * @param fd: Map server's fd
+ * @param account_id: Account ID requesting
+ * @param guild_id: Guild ID requesting
+ * @param flag: Additional parameters
+ * @return True on success or false on failure
+ */
 bool mapif_load_guild_storage(int fd,uint32 account_id,int guild_id, char flag)
 {
 	if( SQL_ERROR == Sql_Query(sql_handle, "SELECT `guild_id` FROM `%s` WHERE `guild_id`='%d'", schema_config.guild_db, guild_id) )
@@ -195,7 +203,7 @@ bool mapif_load_guild_storage(int fd,uint32 account_id,int guild_id, char flag)
 		WFIFOB(fd,12) = flag; //1 open storage, 0 don't open
 		guild_storage_fromsql(guild_id, (struct s_storage*)WFIFOP(fd,13));
 		WFIFOSET(fd, WFIFOW(fd,2));
-		return false;
+		return true;
 	}
 	// guild does not exist
 	Sql_FreeResult(sql_handle);
@@ -205,7 +213,7 @@ bool mapif_load_guild_storage(int fd,uint32 account_id,int guild_id, char flag)
 	WFIFOL(fd,4) = account_id;
 	WFIFOL(fd,8) = 0;
 	WFIFOSET(fd, 12);
-	return true;
+	return false;
 }
 
 void mapif_save_guild_storage_ack(int fd,uint32 account_id,int guild_id,int fail)
@@ -227,6 +235,11 @@ void mapif_parse_LoadGuildStorage(int fd)
 	mapif_load_guild_storage(fd,RFIFOL(fd,2),RFIFOL(fd,6),1);
 }
 
+/**
+ * Save guild storage data from map server
+ * @param fd: Map server's fd
+ * @return True on success or false on failure
+ */
 bool mapif_parse_SaveGuildStorage(int fd)
 {
 	int guild_id;
diff --git a/src/common/mmo.hpp b/src/common/mmo.hpp
index 7b7716bf2e..5a8a966441 100644
--- a/src/common/mmo.hpp
+++ b/src/common/mmo.hpp
@@ -64,7 +64,7 @@
 #define MAX_GUILDPOSITION 20	///Increased max guild positions to accomodate for all members [Valaris] (removed) [PoW]
 #define MAX_GUILDEXPULSION 32 ///Max Guild expulsion
 #define MAX_GUILDALLIANCE 16 ///Max Guild alliance
-#define MAX_GUILDSKILL	15 ///Increased max guild skills because of new skills [Sara-chan]
+#define MAX_GUILDSKILL	17 ///Max Guild skills
 #define MAX_GUILDLEVEL 50 ///Max Guild level
 #define MAX_GUARDIANS 8	///Local max per castle. If this value is increased, need to add more fields on MySQL `guild_castle` table [Skotlex]
 #define MAX_QUEST_OBJECTIVES 3 ///Max quest objectives for a quest
@@ -370,7 +370,7 @@ struct s_storage {
 	bool lock; ///< If locked, can't use storage when item bound retrieval
 	uint32 id; ///< Account ID / Character ID / Guild ID (owner of storage)
 	enum storage_type type; ///< Type of storage (inventory, cart, storage, guild storage)
-	uint16 max_amount;
+	uint16 max_amount; ///< Maximum amount of items in storage
 	uint8 stor_id; ///< Storage ID
 	struct {
 		unsigned get : 1;
@@ -701,6 +701,20 @@ struct guild_castle {
 	int temp_guardians_max;
 };
 
+/// Guild Permissions
+enum e_guild_permission {
+	GUILD_PERM_INVITE	= 0x001,
+	GUILD_PERM_EXPEL	= 0x010,
+#if PACKETVER >= 20140205
+	GUILD_PERM_STORAGE	= 0x100,
+	GUILD_PERM_ALL		= GUILD_PERM_INVITE|GUILD_PERM_EXPEL|GUILD_PERM_STORAGE,
+#else
+	GUILD_PERM_ALL		= GUILD_PERM_INVITE|GUILD_PERM_EXPEL,
+#endif
+	GUILD_PERM_MASK		= GUILD_PERM_ALL,
+	GUILD_PERM_DEFAULT	= GUILD_PERM_ALL,
+};
+
 struct fame_list {
 	int id;
 	int fame;
@@ -742,6 +756,7 @@ enum e_guild_skill {
 	GD_EMERGENCYCALL=10013,
 	GD_DEVELOPMENT=10014,
 	GD_ITEMEMERGENCYCALL=10015,
+	GD_GUILD_STORAGE=10016,
 	GD_MAX,
 };
 
diff --git a/src/config/packets.hpp b/src/config/packets.hpp
index 44aa45c5d2..30932fb6a6 100644
--- a/src/config/packets.hpp
+++ b/src/config/packets.hpp
@@ -43,6 +43,12 @@
 	#endif
 #endif
 
+/// Comment to disable the official Guild Storage skill.
+/// When enabled, this will set the guild storage size to the level of the skill * 100.
+#if PACKETVER >= 20131223
+	#define OFFICIAL_GUILD_STORAGE
+#endif
+
 #ifndef DUMP_UNKNOWN_PACKET
 	//#define DUMP_UNKNOWN_PACKET
 #endif
diff --git a/src/map/atcommand.cpp b/src/map/atcommand.cpp
index f46792ed76..51e5a7c00d 100644
--- a/src/map/atcommand.cpp
+++ b/src/map/atcommand.cpp
@@ -919,31 +919,29 @@ ACMD_FUNC(guildstorage)
 {
 	nullpo_retr(-1, sd);
 
-	if (!sd->status.guild_id) {
-		clif_displaymessage(fd, msg_txt(sd,252)); // You are not in a guild.
-		return -1;
-	}
-
 	if (sd->npc_id || sd->state.vending || sd->state.buyingstore || sd->state.trading)
 		return -1;
 
-	if (sd->state.storage_flag == 1) {
-		clif_displaymessage(fd, msg_txt(sd,250)); // You have already opened your storage. Close it first.
-		return -1;
+	switch (storage_guild_storageopen(sd)) {
+		case GSTORAGE_OPEN:
+			clif_displaymessage(fd, msg_txt(sd, 920)); // Guild storage opened.
+			break;
+		case GSTORAGE_STORAGE_ALREADY_OPEN:
+			clif_displaymessage(fd, msg_txt(sd, 250)); // You have already opened your storage. Close it first.
+			return -1;
+		case GSTORAGE_ALREADY_OPEN:
+			clif_displaymessage(fd, msg_txt(sd, 251)); // You have already opened your guild storage. Close it first.
+			return -1;
+		case GSTORAGE_NO_GUILD:
+			clif_displaymessage(fd, msg_txt(sd, 252)); // You are not in a guild.
+			return -1;
+		case GSTORAGE_NO_STORAGE:
+			clif_displaymessage(fd, msg_txt(sd, 786)); // The guild does not have a guild storage.
+			return -1;
+		case GSTORAGE_NO_PERMISSION:
+			clif_displaymessage(fd, msg_txt(sd, 787)); // You do not have permission to use the guild storage.
+			return -1;
 	}
-
-	if (sd->state.storage_flag == 2) {
-		clif_displaymessage(fd, msg_txt(sd,251)); // You have already opened your guild storage. Close it first.
-		return -1;
-	}
-
-	if (sd->state.storage_flag == 3) {
-		clif_displaymessage(fd, msg_txt(sd,250)); // You have already opened your storage. Close it first.
-		return -1;
-	}
-
-	storage_guild_storageopen(sd);
-	clif_displaymessage(fd, msg_txt(sd,920)); // Guild storage opened.
 	return 0;
 }
 
diff --git a/src/map/guild.cpp b/src/map/guild.cpp
index d781726ec3..eca6f710f4 100644
--- a/src/map/guild.cpp
+++ b/src/map/guild.cpp
@@ -594,7 +594,7 @@ int guild_invite(struct map_session_data *sd, struct map_session_data *tsd) {
 	if(tsd==NULL || g==NULL)
 		return 0;
 
-	if( (i=guild_getposition(sd))<0 || !(g->position[i].mode&0x0001) )
+	if( (i=guild_getposition(sd))<0 || !(g->position[i].mode&GUILD_PERM_INVITE) )
 		return 0; //Invite permission.
 
 	if(!battle_config.invite_request_check) {
@@ -806,7 +806,7 @@ int guild_expulsion(struct map_session_data* sd, int guild_id, uint32 account_id
 	if(sd->status.guild_id!=guild_id)
 		return 0;
 
-	if( (ps=guild_getposition(sd))<0 || !(g->position[ps].mode&0x0010) )
+	if( (ps=guild_getposition(sd))<0 || !(g->position[ps].mode&GUILD_PERM_EXPEL) )
 		return 0;	//Expulsion permission
 
 	//Can't leave inside guild castles.
@@ -1092,14 +1092,11 @@ int guild_memberposition_changed(struct guild *g,int idx,int pos) {
 /*====================================================
  * Change guild title or member
  *---------------------------------------------------*/
-int guild_change_position(int guild_id,int idx,
-	int mode,int exp_mode,const char *name) {
+int guild_change_position(int guild_id,int idx, int mode, int exp_mode, const char *name) {
 	struct guild_position p;
 
 	exp_mode = cap_value(exp_mode, 0, battle_config.guild_exp_limit);
-	//Mode 0x01 <- Invite
-	//Mode 0x10 <- Expel.
-	p.mode=mode&0x11;
+	p.mode = mode&GUILD_PERM_ALL;
 	p.exp_mode=exp_mode;
 	safestrncpy(p.name,name,NAME_LENGTH);
 	return intif_guild_position(guild_id,idx,&p);
diff --git a/src/map/script_constants.hpp b/src/map/script_constants.hpp
index c23254cdcd..5e57e738ae 100644
--- a/src/map/script_constants.hpp
+++ b/src/map/script_constants.hpp
@@ -7228,6 +7228,14 @@
 	export_constant(MD_STATUS_IMMUNE);
 	export_constant(MD_SKILL_IMMUNE);
 
+	/* guild storage flags */
+	export_constant(GSTORAGE_OPEN);
+	export_constant(GSTORAGE_STORAGE_ALREADY_OPEN);
+	export_constant(GSTORAGE_ALREADY_OPEN);
+	export_constant(GSTORAGE_NO_GUILD);
+	export_constant(GSTORAGE_NO_STORAGE);
+	export_constant(GSTORAGE_NO_PERMISSION);
+
 	#undef export_constant
 	#undef export_constant2
 	#undef export_parameter
diff --git a/src/map/storage.cpp b/src/map/storage.cpp
index 4894b86a71..1186a271b2 100644
--- a/src/map/storage.cpp
+++ b/src/map/storage.cpp
@@ -589,34 +589,48 @@ char storage_guild_storageopen(struct map_session_data* sd)
 	nullpo_ret(sd);
 
 	if(sd->status.guild_id <= 0)
-		return 2;
+		return GSTORAGE_NO_GUILD;
 
-	if(sd->state.storage_flag)
-		return 1; //Can't open both storages at a time.
+#ifdef OFFICIAL_GUILD_STORAGE
+	if (!guild_checkskill(sd->guild, GD_GUILD_STORAGE))
+		return GSTORAGE_NO_STORAGE; // Can't open storage if the guild has not learned the skill
+#endif
+
+	if (sd->state.storage_flag == 2)
+		return GSTORAGE_ALREADY_OPEN; // Guild storage already open.
+	else if (sd->state.storage_flag)
+		return GSTORAGE_STORAGE_ALREADY_OPEN; // Can't open both storages at a time.
+
+#if PACKETVER >= 20140205
+	int pos;
+
+	if ((pos = guild_getposition(sd)) < 0 || !(sd->guild->position[pos].mode&GUILD_PERM_STORAGE))
+		return GSTORAGE_NO_PERMISSION; // Guild member doesn't have permission
+#endif
 
 	if( !pc_can_give_items(sd) ) { //check is this GM level can open guild storage and store items [Lupus]
 		clif_displaymessage(sd->fd, msg_txt(sd,246));
-		return 1;
+		return GSTORAGE_ALREADY_OPEN;
 	}
 
 	if((gstor = guild2storage2(sd->status.guild_id)) == NULL) {
 		intif_request_guild_storage(sd->status.account_id,sd->status.guild_id);
-		return 0;
+		return GSTORAGE_OPEN;
 	}
 
 	if(gstor->status)
-		return 1;
+		return GSTORAGE_ALREADY_OPEN;
 
 	if( gstor->lock )
-		return 1;
+		return GSTORAGE_ALREADY_OPEN;
 
 	gstor->status = true;
 	sd->state.storage_flag = 2;
 	storage_sortitem(gstor->u.items_guild, ARRAYLENGTH(gstor->u.items_guild));
 	clif_storagelist(sd, gstor->u.items_guild, ARRAYLENGTH(gstor->u.items_guild), "Guild Storage");
-	clif_updatestorageamount(sd, gstor->amount, MAX_GUILD_STORAGE);
+	clif_updatestorageamount(sd, gstor->amount, gstor->max_amount);
 
-	return 0;
+	return GSTORAGE_OPEN;
 }
 
 /**
@@ -655,7 +669,7 @@ bool storage_guild_additem(struct map_session_data* sd, struct s_storage* stor,
 	}
 
 	if(itemdb_isstackable2(id)) { //Stackable
-		for(i = 0; i < MAX_GUILD_STORAGE; i++) {
+		for(i = 0; i < stor->max_amount; i++) {
 			if(compare_item(&stor->u.items_guild[i], item_data)) {
 				if( amount > MAX_AMOUNT - stor->u.items_guild[i].amount || ( id->stack.guildstorage && amount > id->stack.amount - stor->u.items_guild[i].amount ) )
 					return false;
@@ -669,15 +683,15 @@ bool storage_guild_additem(struct map_session_data* sd, struct s_storage* stor,
 	}
 
 	//Add item
-	for(i = 0; i < MAX_GUILD_STORAGE && stor->u.items_guild[i].nameid; i++);
-	if(i >= MAX_GUILD_STORAGE)
+	for(i = 0; i < stor->max_amount && stor->u.items_guild[i].nameid; i++);
+	if(i >= stor->max_amount)
 		return false;
 
 	memcpy(&stor->u.items_guild[i],item_data,sizeof(stor->u.items_guild[0]));
 	stor->u.items_guild[i].amount = amount;
 	stor->amount++;
 	clif_storageitemadded(sd,&stor->u.items_guild[i],i,amount);
-	clif_updatestorageamount(sd, stor->amount, MAX_GUILD_STORAGE);
+	clif_updatestorageamount(sd, stor->amount, stor->max_amount);
 	stor->dirty = true;
 	return true;
 }
@@ -703,7 +717,7 @@ bool storage_guild_additem2(struct s_storage* stor, struct item* item, int amoun
 		return false;
 
 	if (itemdb_isstackable2(id)) { // Stackable
-		for (i = 0; i < MAX_GUILD_STORAGE; i++) {
+		for (i = 0; i < stor->max_amount; i++) {
 			if (compare_item(&stor->u.items_guild[i], item)) {
 				// Set the amount, make it fit with max amount
 				amount = min(amount, ((id->stack.guildstorage) ? id->stack.amount : MAX_AMOUNT) - stor->u.items_guild[i].amount);
@@ -717,8 +731,8 @@ bool storage_guild_additem2(struct s_storage* stor, struct item* item, int amoun
 	}
 
 	// Add the item
-	for (i = 0; i < MAX_GUILD_STORAGE && stor->u.items_guild[i].nameid; i++);
-	if (i >= MAX_GUILD_STORAGE)
+	for (i = 0; i < stor->max_amount && stor->u.items_guild[i].nameid; i++);
+	if (i >= stor->max_amount)
 		return false;
 
 	memcpy(&stor->u.items_guild[i], item, sizeof(stor->u.items_guild[0]));
@@ -749,7 +763,7 @@ bool storage_guild_delitem(struct map_session_data* sd, struct s_storage* stor,
 	if(!stor->u.items_guild[n].amount) {
 		memset(&stor->u.items_guild[n],0,sizeof(stor->u.items_guild[0]));
 		stor->amount--;
-		clif_updatestorageamount(sd, stor->amount, MAX_GUILD_STORAGE);
+		clif_updatestorageamount(sd, stor->amount, stor->max_amount);
 	}
 
 	clif_storageitemremoved(sd,n,amount);
@@ -769,7 +783,7 @@ void storage_guild_storageadd(struct map_session_data* sd, int index, int amount
 	nullpo_retv(sd);
 	nullpo_retv(stor = guild2storage2(sd->status.guild_id));
 
-	if( !stor->status || stor->amount > MAX_GUILD_STORAGE )
+	if( !stor->status || stor->amount > stor->max_amount )
 		return;
 
 	if( index < 0 || index >= MAX_INVENTORY )
@@ -812,7 +826,7 @@ void storage_guild_storageget(struct map_session_data* sd, int index, int amount
 	if(!stor->status)
 		return;
 
-	if(index < 0 || index >= MAX_GUILD_STORAGE)
+	if(index < 0 || index >= stor->max_amount)
 		return;
 
 	if(stor->u.items_guild[index].nameid == 0)
@@ -847,7 +861,7 @@ void storage_guild_storageaddfromcart(struct map_session_data* sd, int index, in
 	nullpo_retv(sd);
 	nullpo_retv(stor = guild2storage2(sd->status.guild_id));
 
-	if( !stor->status || stor->amount > MAX_GUILD_STORAGE )
+	if( !stor->status || stor->amount > stor->max_amount )
 		return;
 
 	if( index < 0 || index >= MAX_CART )
@@ -885,7 +899,7 @@ void storage_guild_storagegettocart(struct map_session_data* sd, int index, int
 	if(!stor->status)
 		return;
 
-	if(index < 0 || index >= MAX_GUILD_STORAGE)
+	if(index < 0 || index >= stor->max_amount)
 		return;
 
 	if(stor->u.items_guild[index].nameid == 0)
diff --git a/src/map/storage.hpp b/src/map/storage.hpp
index f1f2a0c623..a698bfeb3b 100644
--- a/src/map/storage.hpp
+++ b/src/map/storage.hpp
@@ -20,6 +20,16 @@ enum e_storage_add {
 	STORAGE_ADD_INVALID,
 };
 
+/// Guild storage flags
+enum e_guild_storage_flags : uint8 {
+	GSTORAGE_OPEN = 0,
+	GSTORAGE_STORAGE_ALREADY_OPEN,
+	GSTORAGE_ALREADY_OPEN,
+	GSTORAGE_NO_GUILD,
+	GSTORAGE_NO_STORAGE,
+	GSTORAGE_NO_PERMISSION
+};
+
 const char *storage_getName(uint8 id);
 bool storage_exists(uint8 id);