diff --git a/core/Network/TLS/Handshake/Common13.hs b/core/Network/TLS/Handshake/Common13.hs
index d14e87ae5..6aee5ee9f 100644
--- a/core/Network/TLS/Handshake/Common13.hs
+++ b/core/Network/TLS/Handshake/Common13.hs
@@ -590,5 +590,5 @@ setRTT :: Context -> Millisecond -> IO ()
 setRTT ctx chSentTime = do
     shRecvTime <- getCurrentTimeFromBase
     let rtt' = shRecvTime - chSentTime
-        rtt = if rtt' == 0 then 5 else rtt'
+        rtt = if rtt' == 0 then 10 else rtt'
     modifyTLS13State ctx $ \st -> st{tls13stRTT = rtt}