diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 205cc5d..9ff0795 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -5576,6 +5576,7 @@
 
 # -nbio is added to prevent s_client from blocking in case of duplicated
 # messages at the end of the handshake
+requires_openssl_legacy
 requires_config_enabled MBEDTLS_SSL_PROTO_DTLS
 requires_config_enabled MBEDTLS_RSA_C
 requires_config_enabled MBEDTLS_ECDSA_C