diff --git a/launcher/ui/pages/instance/McClient.hpp b/launcher/ui/pages/instance/McClient.hpp
index 1dc88cc30..afbb64739 100644
--- a/launcher/ui/pages/instance/McClient.hpp
+++ b/launcher/ui/pages/instance/McClient.hpp
@@ -150,8 +150,8 @@ private:
         }
     }
 
-    void writeString(QByteArray &data, std::string value) {
-        data.append(value);
+    void writeString(QByteArray &data, const std::string &value) {
+        data.append(value.c_str());
     }
 
     void writePacketToSocket(QByteArray &data) {