diff --git a/testssl.sh b/testssl.sh
index c0e599a..8bc6fc0 100755
--- a/testssl.sh
+++ b/testssl.sh
@@ -4272,11 +4272,17 @@ socksend_tls_clienthello() {
           ,00                      # server_name type (hostname)
           ,00, $len_servername_hex # server_name length. We assume len(hostname) < FF - 9
           ,$servername_hexstr      # server_name target
-          ,$extension_signature_algorithms
           ,$extension_heartbeat
           ,$extension_session_ticket
           ,$extension_next_protocol"
 
+          # RFC 5246 says that clients MUST NOT offer the signature algorithms
+          # extension if they are offering TLS versions prior to 1.2.
+          if [[ "$tls_low_byte" == "03" ]]; then
+               all_extensions="$all_extensions
+               ,$extension_signature_algorithms"
+          fi
+
           if $ecc_cipher_suite_found; then
                all_extensions="$all_extensions
                ,$extensions_ecc"