diff --git a/src/ChatCommands.cc b/src/ChatCommands.cc
index 6c4a5306..d4776f8c 100644
--- a/src/ChatCommands.cc
+++ b/src/ChatCommands.cc
@@ -369,18 +369,21 @@ static void proxy_command_get_player_card(shared_ptr<ServerState>,
 static void server_command_send_client(shared_ptr<ServerState>, shared_ptr<Lobby>,
     shared_ptr<Client> c, const std::u16string& args) {
   string data = parse_data_string(encode_sjis(args));
+  data.resize((data.size() + 3) & (~3));
   c->channel.send(data);
 }
 
 static void proxy_command_send_client(shared_ptr<ServerState>,
     ProxyServer::LinkedSession& session, const std::u16string& args) {
   string data = parse_data_string(encode_sjis(args));
+  data.resize((data.size() + 3) & (~3));
   session.client_channel.send(data);
 }
 
 static void proxy_command_send_server(shared_ptr<ServerState>,
     ProxyServer::LinkedSession& session, const std::u16string& args) {
   string data = parse_data_string(encode_sjis(args));
+  data.resize((data.size() + 3) & (~3));
   session.server_channel.send(data);
 }
 
diff --git a/src/ServerShell.cc b/src/ServerShell.cc
index 0e04b7dc..8d3dfcc9 100644
--- a/src/ServerShell.cc
+++ b/src/ServerShell.cc
@@ -583,12 +583,10 @@ session with ID 17205AE4, run the command `on 17205AE4 sc 1D 00 04 00`.\n\
 
   } else if ((command_name == "sc") || (command_name == "ss")) {
     string data = parse_data_string(command_args, nullptr, ParseDataFlags::ALLOW_FILES);
-    if (data.size() & 3) {
-      throw invalid_argument("data size is not a multiple of 4");
-    }
     if (data.size() == 0) {
       throw invalid_argument("no data given");
     }
+    data.resize((data.size() + 3) & (~3));
 
     shared_ptr<ProxyServer::LinkedSession> proxy_session;
     try {