Index: nss/lib/ssl/sslsock.c
===================================================================
--- nss.orig/lib/ssl/sslsock.c
+++ nss/lib/ssl/sslsock.c
@@ -86,7 +86,7 @@ static sslOptions ssl_defaults = {
     .enableSignedCertTimestamps = PR_FALSE,
     .requireDHENamedGroups = PR_FALSE,
     .enable0RttData = PR_FALSE,
-    .enableTls13CompatMode = PR_FALSE,
+    .enableTls13CompatMode = PR_TRUE,
     .enableDtls13VersionCompat = PR_FALSE,
     .enableDtlsShortHeader = PR_FALSE,
     .enableHelloDowngradeCheck = PR_FALSE,