diff --git a/testssl.sh b/testssl.sh
index 0ab1c6a..3cd77dc 100755
--- a/testssl.sh
+++ b/testssl.sh
@@ -13213,11 +13213,11 @@ prepare_tls_clienthello() {
                # Supported Groups Extension
                extension_supported_groups="
                00, 0a,                    # Type: Supported Elliptic Curves , see RFC 4492
-               00, 3e, 00, 3c,            # lengths
+               00, 42, 00, 40,            # lengths
                00, 0e, 00, 0d, 00, 19, 00, 1c, 00, 1e, 00, 0b, 00, 0c, 00, 1b,
                00, 18, 00, 09, 00, 0a, 00, 1a, 00, 16, 00, 17, 00, 1d, 00, 08,
                00, 06, 00, 07, 00, 14, 00, 15, 00, 04, 00, 05, 00, 12, 00, 13,
-               00, 01, 00, 02, 00, 03, 00, 0f, 00, 10, 00, 11"
+               00, 01, 00, 02, 00, 03, 00, 0f, 00, 10, 00, 11, 01, 00, 01, 01"
           elif [[ 0x$tls_low_byte -gt 0x03 ]]; then
                # Supported Groups Extension
                if [[ ! "$process_full" =~ all ]] || ( [[ ! "$OSSL_NAME" =~ LibreSSL ]] && \