diff --git a/src/http_tracker_connection.cpp b/src/http_tracker_connection.cpp
index 321a57df7..64dea2e2e 100755
--- a/src/http_tracker_connection.cpp
+++ b/src/http_tracker_connection.cpp
@@ -432,6 +432,7 @@ namespace libtorrent
 			{
 				m_send_buffer += "ipv6=";
 				m_send_buffer += req.ipv6;
+				m_send_buffer += '&';
 			}
 
 			// extension that tells the tracker that