diff --git a/cockatrice/src/window_main.cpp b/cockatrice/src/window_main.cpp
index f2268911..61c248c9 100644
--- a/cockatrice/src/window_main.cpp
+++ b/cockatrice/src/window_main.cpp
@@ -78,7 +78,7 @@ 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.\nYou may only use A-Z, a-z, 0-9, _, ., and - in your 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));
@@ -261,7 +261,7 @@ void MainWindow::loginError(Response::ResponseCode r, QString reasonStr, quint32
             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."));
+            QMessageBox::critical(this, tr("Error"), tr("Invalid username.\nYou may only use A-Z, a-z, 0-9, _, ., and - in your username."));
             break;
         case Response::RespRegistrationRequired:
             QMessageBox::critical(this, tr("Error"), tr("This server requires user registration."));
diff --git a/servatrice/src/servatrice_database_interface.cpp b/servatrice/src/servatrice_database_interface.cpp
index fa52e09c..dd2b2261 100644
--- a/servatrice/src/servatrice_database_interface.cpp
+++ b/servatrice/src/servatrice_database_interface.cpp
@@ -98,22 +98,8 @@ bool Servatrice_DatabaseInterface::execSqlQuery(QSqlQuery *query)
 
 bool Servatrice_DatabaseInterface::usernameIsValid(const QString &user)
 {
-    QString result;
-    result.reserve(user.size());
-    foreach (const QChar& c, user) {
-        switch (c.category()) {
-        case QChar::Letter_Uppercase:       //[A-Z]
-        case QChar::Letter_Lowercase:       //[a-z]
-        case QChar::Number_DecimalDigit:    //[0-9]
-        case QChar::Punctuation_Connector:  //[_]
-        case QChar::Punctuation_Dash:       //[-]
-            result += c;
-        default: 
-            break;
-        }
-    }
-    result = result.trimmed();
-    return (result.size() == user.size());
+    static QRegExp re = QRegExp("^[a-zA-Z0-9_\-\.]+$");
+    return re.exactMatch(user);
 }
 
 bool Servatrice_DatabaseInterface::getRequireRegistration()