diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 54ea129..1114056 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -940,6 +940,13 @@
              return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
         }
 
+        if( conf->endpoint == MBEDTLS_SSL_IS_SERVER )
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS 1.3 server is not supported yet." ) );
+            return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+        }
+
+
         MBEDTLS_SSL_DEBUG_MSG( 4, ( "The SSL configuration is TLS 1.3 or TLS 1.2." ) );
         return( 0 );
     }