diff --git a/src/CommandFormats.hh b/src/CommandFormats.hh
index 4c2bd2b3..0a1567b5 100644
--- a/src/CommandFormats.hh
+++ b/src/CommandFormats.hh
@@ -1198,7 +1198,7 @@ struct C_Login_PC_9D {
   le_uint64_t unused;
   le_uint32_t sub_version;
   uint8_t is_extended; // If 1, structure has extended format
-  uint8_t unknown_a1; // Always 1?
+  uint8_t language; // 0 = JP, 1 = EN, 2 = DE (?), 3 = FR (?), 4 = ES
   parray<uint8_t, 0x2> unused3; // Always zeroes?
   ptext<char, 0x10> unused1; // Same as unused1/unused2 in 9A
   ptext<char, 0x10> unused2;
diff --git a/src/ProxyCommands.cc b/src/ProxyCommands.cc
index 33aae738..6dd5b48f 100644
--- a/src/ProxyCommands.cc
+++ b/src/ProxyCommands.cc
@@ -130,7 +130,7 @@ static HandlerResult process_server_gc_9A(shared_ptr<ServerState>,
   cmd.unused = 0;
   cmd.sub_version = session.sub_version;
   cmd.is_extended = session.remote_guild_card_number ? 0 : 1;
-  cmd.unknown_a1 = 1;
+  cmd.language = session.language;
   cmd.serial_number = string_printf("%08" PRIX32 "", session.license->serial_number);
   cmd.access_key = session.license->access_key;
   cmd.serial_number2 = cmd.serial_number;
@@ -213,7 +213,7 @@ static HandlerResult process_server_pc_gc_patch_02_17(shared_ptr<ServerState> s,
     cmd.unused = 0xFFFFFFFFFFFF0000;
     cmd.sub_version = session.sub_version;
     cmd.is_extended = 0;
-    cmd.unknown_a1 = 1;
+    cmd.language = session.language;
     cmd.serial_number = string_printf("%08" PRIX32 "",
         session.license->serial_number);
     cmd.access_key = session.license->access_key;
diff --git a/src/ProxyServer.cc b/src/ProxyServer.cc
index 3a6c4942..3c99845e 100644
--- a/src/ProxyServer.cc
+++ b/src/ProxyServer.cc
@@ -253,6 +253,7 @@ void ProxyServer::UnlinkedSession::on_input(Channel& ch, uint16_t command, uint3
   bool should_close_unlinked_session = false;
   shared_ptr<const License> license;
   uint32_t sub_version = 0;
+  uint8_t language = 1; // Default = English
   string character_name;
   ClientConfigBB client_config;
   string login_command_bb;
@@ -269,6 +270,7 @@ void ProxyServer::UnlinkedSession::on_input(Channel& ch, uint16_t command, uint3
       license = session->server->state->license_manager->verify_pc(
           stoul(cmd.serial_number, nullptr, 16), cmd.access_key);
       sub_version = cmd.sub_version;
+      language = cmd.language;
       character_name = cmd.name;
 
     } else if (session->version == GameVersion::GC) {
@@ -282,6 +284,7 @@ void ProxyServer::UnlinkedSession::on_input(Channel& ch, uint16_t command, uint3
       license = session->server->state->license_manager->verify_gc(
           stoul(cmd.serial_number, nullptr, 16), cmd.access_key);
       sub_version = cmd.sub_version;
+      language = cmd.language;
       character_name = cmd.name;
       client_config.cfg = cmd.client_config.cfg;
 
@@ -362,6 +365,7 @@ void ProxyServer::UnlinkedSession::on_input(Channel& ch, uint16_t command, uint3
                 move(session->channel),
                 session->detector_crypt,
                 sub_version,
+                language,
                 character_name);
           }
         } catch (const exception& e) {
@@ -426,6 +430,7 @@ ProxyServer::LinkedSession::LinkedSession(
     enable_remote_ip_crc_patch(false),
     version(version),
     sub_version(0), // This is set during resume()
+    language(1), // Default = English. This is also set during resume()
     remote_guild_card_number(0),
     enable_chat_filter(true),
     switch_assist(false),
@@ -483,8 +488,10 @@ void ProxyServer::LinkedSession::resume(
     Channel&& client_channel,
     shared_ptr<PSOBBMultiKeyDetectorEncryption> detector_crypt,
     uint32_t sub_version,
+    uint8_t language,
     const string& character_name) {
   this->sub_version = sub_version;
+  this->language = language;
   this->character_name = character_name;
   this->resume_inner(move(client_channel), detector_crypt);
 }
@@ -499,6 +506,7 @@ void ProxyServer::LinkedSession::resume(
 
 void ProxyServer::LinkedSession::resume(Channel&& client_channel) {
   this->sub_version = 0;
+  this->language = 1;
   this->character_name.clear();
   this->resume_inner(move(client_channel), nullptr);
 }
diff --git a/src/ProxyServer.hh b/src/ProxyServer.hh
index 785665cf..7ad2211e 100644
--- a/src/ProxyServer.hh
+++ b/src/ProxyServer.hh
@@ -52,6 +52,7 @@ public:
 
     GameVersion version;
     uint32_t sub_version;
+    uint8_t language;
     std::string character_name;
     std::string login_command_bb;
 
@@ -121,6 +122,7 @@ public:
         Channel&& client_channel,
         std::shared_ptr<PSOBBMultiKeyDetectorEncryption> detector_crypt,
         uint32_t sub_version,
+        uint8_t language,
         const std::string& character_name);
     void resume(
         Channel&& client_channel,