diff --git a/cockatrice/src/window_main.cpp b/cockatrice/src/window_main.cpp
index 186ab2fb..f0ac4914 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.\nAvailable chars: [a-z][A-Z][0-9][-_]"); 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));