diff --git a/cockatrice/src/window_main.cpp b/cockatrice/src/window_main.cpp
index de65d4d1..ce85f37f 100644
--- a/cockatrice/src/window_main.cpp
+++ b/cockatrice/src/window_main.cpp
@@ -83,7 +83,7 @@ void MainWindow::processConnectionClosedEvent(const Event_ConnectionClosed &even
             break;
         }
         case Event_ConnectionClosed::SERVER_SHUTDOWN: reasonStr = tr("Scheduled server shutdown."); break;
-        case Event_ConnectionClosed::USERNAMEINVALID: reasonStr = tr("Invalid username.\nYou may only use A-Z, a-z, 0-9, _, ., and - in your username."); break;
+        case Event_ConnectionClosed::USERNAMEINVALID: reasonStr = tr("Invalid username."); break;
         default: reasonStr = QString::fromStdString(event.reason_str());
     }
     QMessageBox::critical(this, tr("Connection closed"), tr("The server has terminated your connection.\nReason: %1").arg(reasonStr));
@@ -306,9 +306,12 @@ void MainWindow::loginError(Response::ResponseCode r, QString reasonStr, quint32
             QMessageBox::critical(this, tr("Error"), bannedStr);
             break;
         }
-        case Response::RespUsernameInvalid:
-            QMessageBox::critical(this, tr("Error"), tr("Invalid username.\nYou may only use A-Z, a-z, 0-9, _, ., and - in your username."));
+        case Response::RespUsernameInvalid: {
+            QString errorStr;
+            extractInvalidUsernameMessage(reasonStr, errorStr);
+            QMessageBox::critical(this, tr("Error"), errorStr);
             break;
+        }
         case Response::RespRegistrationRequired:
             if (QMessageBox::question(this, tr("Error"), tr("This server requires user registration. Do you want to register now?"), QMessageBox::Yes | QMessageBox::No) == QMessageBox::Yes) {
                 actRegister();
@@ -332,6 +335,36 @@ void MainWindow::loginError(Response::ResponseCode r, QString reasonStr, quint32
     actConnect();
 }
 
+void MainWindow::extractInvalidUsernameMessage(QString & in, QString & out)
+{
+    out = tr("Invalid username.") + "<br/>";
+    QStringList rules = in.split(QChar('|'));
+    if (rules.size() == 7)
+    {
+        out += tr("The username must respect these rules:") + "<br/><ul>"
+            + "<li>" + tr("length between %1 and %2 characters").arg(rules.at(0)).arg(rules.at(1)) + "</li>";
+        if(rules.at(2).toInt() > 0)
+            out += "<li>" + tr("it can contain lowercase characters") + "</li>";
+        if(rules.at(3).toInt() > 0)
+            out += "<li>" + tr("it can contain uppercase characters") + "</li>";
+        if(rules.at(4).toInt() > 0)
+            out += "<li>" + tr("it can contain numeric characters") + "</li>";
+        if(rules.at(6).size() > 0)
+            out += "<li>" + tr("it can contain the following punctuation: %1").arg(
+#if QT_VERSION < 0x050000
+    Qt::escape(rules.at(6))
+#else
+    rules.at(6).toHtmlEscaped()
+#endif
+        ) + "</li>";
+        if(rules.at(5).toInt() > 0)
+            out += "<li>" + tr("the first character can't be a punctuation") + "</li>";
+        out += "</ul>";
+    } else {
+        out += tr("You may only use A-Z, a-z, 0-9, _, ., and - in your username.");
+    }
+}
+
 void MainWindow::registerError(Response::ResponseCode r, QString reasonStr, quint32 endTime)
 {
     switch (r) {
@@ -362,36 +395,10 @@ void MainWindow::registerError(Response::ResponseCode r, QString reasonStr, quin
             QMessageBox::critical(this, tr("Error"), bannedStr);
             break;
         }
-        case Response::RespUsernameInvalid:
-        {
-            QString error = tr("Invalid username.") + "<br/>";
-            QStringList rules = reasonStr.split(QChar('|'));
-            if (rules.size() == 7)
-            {
-                error += tr("The username must respect these rules:") + "<br/><ul>"
-                    + "<li>" + tr("length between %1 and %2 characters").arg(rules.at(0)).arg(rules.at(1)) + "</li>";
-                if(rules.at(2).toInt() > 0)
-                    error += "<li>" + tr("it can contain lowercase characters") + "</li>";
-                if(rules.at(3).toInt() > 0)
-                    error += "<li>" + tr("it can contain uppercase characters") + "</li>";
-                if(rules.at(4).toInt() > 0)
-                    error += "<li>" + tr("it can contain numeric characters") + "</li>";
-                if(rules.at(6).size() > 0)
-                    error += "<li>" + tr("it can contain the following punctuation: %1").arg(
-#if QT_VERSION < 0x050000
-            Qt::escape(rules.at(6))
-#else
-            rules.at(6).toHtmlEscaped()
-#endif
-                ) + "</li>";
-                if(rules.at(5).toInt() > 0)
-                    error += "<li>" + tr("the first character can't be a punctuation") + "</li>";
-                error += "</ul>";
-            } else {
-                error += tr("You may only use A-Z, a-z, 0-9, _, ., and - in your username.");
-            }
-
-            QMessageBox::critical(this, tr("Error"), error);
+        case Response::RespUsernameInvalid: {
+            QString errorStr;
+            extractInvalidUsernameMessage(reasonStr, errorStr);
+            QMessageBox::critical(this, tr("Error"), errorStr);
             break;
         }
         case Response::RespRegistrationFailed:
diff --git a/cockatrice/src/window_main.h b/cockatrice/src/window_main.h
index 57b9e780..9bde26b1 100644
--- a/cockatrice/src/window_main.h
+++ b/cockatrice/src/window_main.h
@@ -109,6 +109,7 @@ public:
 protected:
     void closeEvent(QCloseEvent *event);
     void changeEvent(QEvent *event);
+    void extractInvalidUsernameMessage(QString & in, QString & out);
 };
 
 #endif
diff --git a/common/server_protocolhandler.cpp b/common/server_protocolhandler.cpp
index 46e2bb83..7df87189 100644
--- a/common/server_protocolhandler.cpp
+++ b/common/server_protocolhandler.cpp
@@ -388,7 +388,12 @@ Response::ResponseCode Server_ProtocolHandler::cmdLogin(const Command_Login &cmd
         }
         case NotLoggedIn: return Response::RespWrongPassword;
         case WouldOverwriteOldSession: return Response::RespWouldOverwriteOldSession;
-        case UsernameInvalid: return Response::RespUsernameInvalid;
+        case UsernameInvalid: {
+            Response_Login *re = new Response_Login;
+            re->set_denied_reason_str(reasonStr.toStdString());
+            rc.setResponseExtension(re);
+            return Response::RespUsernameInvalid;
+        }
         case RegistrationRequired: return Response::RespRegistrationRequired;
         case UserIsInactive: return Response::RespAccountNotActivated;
         default: authState = res;
diff --git a/servatrice/src/servatrice_database_interface.cpp b/servatrice/src/servatrice_database_interface.cpp
index 7aa5fa06..b48fb738 100644
--- a/servatrice/src/servatrice_database_interface.cpp
+++ b/servatrice/src/servatrice_database_interface.cpp
@@ -247,8 +247,7 @@ AuthenticationResult Servatrice_DatabaseInterface::checkUserPassword(Server_Prot
         if (!checkSql())
             return UnknownUser;
 
-        QString error;
-        if (!usernameIsValid(user, error))
+        if (!usernameIsValid(user, reasonStr))
             return UsernameInvalid;
         
         if (checkUserIsBanned(handler->getAddress(), user, reasonStr, banSecondsLeft))