diff --git a/src/interfaces.cpp b/src/interfaces.cpp
index 6e3875f..5cbb570 100644
--- a/src/interfaces.cpp
+++ b/src/interfaces.cpp
@@ -1330,7 +1330,7 @@ std::string subconverter(RESPONSE_CALLBACK_ARGS)
     tribool argClashNewField = getUrlArg(argument, "new_name");
     int intSurgeVer = argSurgeVer.size() ? to_int(argSurgeVer, 3) : 3;
     if(argTarget == "auto")
-        matchUserAgent(request.headers["X-User-Agent"], argTarget, argClashNewField, intSurgeVer);
+        matchUserAgent(request.headers["User-Agent"], argTarget, argClashNewField, intSurgeVer);
 
     switch(hash_(argTarget))
     {