diff --git a/programs/ssl/ssl_server2.c b/programs/ssl/ssl_server2.c
index 83bd617..25cdb40 100644
--- a/programs/ssl/ssl_server2.c
+++ b/programs/ssl/ssl_server2.c
@@ -95,6 +95,7 @@
 #define DFL_ECJPAKE_PW          NULL
 #define DFL_PSK_LIST            NULL
 #define DFL_FORCE_CIPHER        0
+#define DFL_TLS13_KEX_MODES     MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_ALL
 #define DFL_RENEGOTIATION       MBEDTLS_SSL_RENEGOTIATION_DISABLED
 #define DFL_ALLOW_LEGACY        -2
 #define DFL_RENEGOTIATE         0
@@ -564,6 +565,9 @@
     char *psk_list;             /* list of PSK id/key pairs for callback    */
     const char *ecjpake_pw;     /* the EC J-PAKE password                   */
     int force_ciphersuite[2];   /* protocol/ciphersuite to use, or all      */
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+    int tls13_kex_modes;        /* supported TLS 1.3 key exchange modes     */
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
     int renegotiation;          /* enable / disable renegotiation           */
     int allow_legacy;           /* allow legacy renegotiation               */
     int renegotiate;            /* attempt renegotiation?                   */
@@ -1478,6 +1482,9 @@
     opt.psk_list            = DFL_PSK_LIST;
     opt.ecjpake_pw          = DFL_ECJPAKE_PW;
     opt.force_ciphersuite[0]= DFL_FORCE_CIPHER;
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+    opt.tls13_kex_modes     = DFL_TLS13_KEX_MODES;
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
     opt.renegotiation       = DFL_RENEGOTIATION;
     opt.allow_legacy        = DFL_ALLOW_LEGACY;
     opt.renegotiate         = DFL_RENEGOTIATE;
@@ -1714,6 +1721,25 @@
             if( opt.exchanges < 0 )
                 goto usage;
         }
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+        else if( strcmp( p, "tls13_kex_modes" ) == 0 )
+        {
+            if( strcmp( q, "psk_pure" ) == 0 )
+                opt.tls13_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK;
+            else if( strcmp(q, "psk_ephemeral" ) == 0 )
+                opt.tls13_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_EPHEMERAL;
+            else if( strcmp(q, "ephemeral_pure" ) == 0 )
+                opt.tls13_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_EPHEMERAL;
+            else if( strcmp(q, "ephemeral_all" ) == 0 )
+                opt.tls13_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_EPHEMERAL_ALL;
+            else if( strcmp( q, "psk_all" ) == 0 )
+                opt.tls13_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_PSK_ALL;
+            else if( strcmp( q, "all" ) == 0 )
+                opt.tls13_kex_modes = MBEDTLS_SSL_TLS13_KEY_EXCHANGE_MODE_ALL;
+            else goto usage;
+        }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+
         else if( strcmp( p, "min_version" ) == 0 )
         {
             if( strcmp( q, "tls1_2" ) == 0 ||
@@ -2610,6 +2636,10 @@
     if( opt.force_ciphersuite[0] != DFL_FORCE_CIPHER )
         mbedtls_ssl_conf_ciphersuites( &conf, opt.force_ciphersuite );
 
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
+    mbedtls_ssl_conf_tls13_key_exchange_modes( &conf, opt.tls13_kex_modes );
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
+
     if( opt.allow_legacy != DFL_ALLOW_LEGACY )
         mbedtls_ssl_conf_legacy_renegotiation( &conf, opt.allow_legacy );
 #if defined(MBEDTLS_SSL_RENEGOTIATION)