diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index 610aa14..6be6c9c 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -927,6 +927,11 @@
 
     unsigned char MBEDTLS_PRIVATE(exported);
 
+    /* This field is temporarily duplicated with mbedtls_ssl_context.minor_ver.
+     * Once runtime negotiation of TLS 1.2 and TLS 1.3 is implemented, it needs
+     * to be studied whether one of them can be removed. */
+    unsigned char MBEDTLS_PRIVATE(minor_ver);    /*!< The TLS version used in the session. */
+
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
 #if defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
     mbedtls_x509_crt *MBEDTLS_PRIVATE(peer_cert);       /*!< peer X.509 cert chain */
@@ -1245,6 +1250,10 @@
 #endif /* MBEDTLS_SSL_RENEGOTIATION */
 
     int MBEDTLS_PRIVATE(major_ver);              /*!< equal to  MBEDTLS_SSL_MAJOR_VERSION_3    */
+
+    /* This field is temporarily duplicated with mbedtls_ssl_context.minor_ver.
+     * Once runtime negotiation of TLS 1.2 and TLS 1.3 is implemented, it needs
+     * to be studied whether one of them can be removed. */
     int MBEDTLS_PRIVATE(minor_ver);              /*!< one of MBEDTLS_SSL_MINOR_VERSION_x macros */
     unsigned MBEDTLS_PRIVATE(badmac_seen);       /*!< records with a bad MAC received    */
 
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index ef391b3..e0a1c24 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -2024,6 +2024,7 @@
     MBEDTLS_SSL_DEBUG_BUF( 3, "server hello, version", buf + 0, 2 );
     mbedtls_ssl_read_version( &ssl->major_ver, &ssl->minor_ver,
                       ssl->conf->transport, buf + 0 );
+    ssl->session_negotiate->minor_ver = ssl->minor_ver;
 
     if( ssl->major_ver < ssl->conf->min_major_ver ||
         ssl->minor_ver < ssl->conf->min_minor_ver ||
diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index ad98850..d82ec04 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -1392,6 +1392,7 @@
 
     mbedtls_ssl_read_version( &ssl->major_ver, &ssl->minor_ver,
                       ssl->conf->transport, buf );
+    ssl->session_negotiate->minor_ver = ssl->minor_ver;
 
     ssl->handshake->max_major_ver = ssl->major_ver;
     ssl->handshake->max_minor_ver = ssl->minor_ver;
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index fe3b5e2..bb5ddc4 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -655,7 +655,6 @@
  * - [in] ciphersuite
  * - [in] master
  * - [in] encrypt_then_mac
- * - [in] trunc_hmac
  * - [in] compression
  * - [in] tls_prf: pointer to PRF to use for key derivation
  * - [in] randbytes: buffer holding ServerHello.random + ClientHello.random
@@ -4488,8 +4487,6 @@
 #define SSL_SERIALIZED_SESSION_CONFIG_MFL 0
 #endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
 
-#define SSL_SERIALIZED_SESSION_CONFIG_TRUNC_HMAC 0
-
 #if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
 #define SSL_SERIALIZED_SESSION_CONFIG_ETM 1
 #else
@@ -4506,9 +4503,8 @@
 #define SSL_SERIALIZED_SESSION_CONFIG_CRT_BIT           1
 #define SSL_SERIALIZED_SESSION_CONFIG_CLIENT_TICKET_BIT 2
 #define SSL_SERIALIZED_SESSION_CONFIG_MFL_BIT           3
-#define SSL_SERIALIZED_SESSION_CONFIG_TRUNC_HMAC_BIT    4
-#define SSL_SERIALIZED_SESSION_CONFIG_ETM_BIT           5
-#define SSL_SERIALIZED_SESSION_CONFIG_TICKET_BIT        6
+#define SSL_SERIALIZED_SESSION_CONFIG_ETM_BIT           4
+#define SSL_SERIALIZED_SESSION_CONFIG_TICKET_BIT        5
 
 #define SSL_SERIALIZED_SESSION_CONFIG_BITFLAG                           \
     ( (uint16_t) (                                                      \
@@ -4516,7 +4512,6 @@
         ( SSL_SERIALIZED_SESSION_CONFIG_CRT           << SSL_SERIALIZED_SESSION_CONFIG_CRT_BIT           ) | \
         ( SSL_SERIALIZED_SESSION_CONFIG_CLIENT_TICKET << SSL_SERIALIZED_SESSION_CONFIG_CLIENT_TICKET_BIT ) | \
         ( SSL_SERIALIZED_SESSION_CONFIG_MFL           << SSL_SERIALIZED_SESSION_CONFIG_MFL_BIT           ) | \
-        ( SSL_SERIALIZED_SESSION_CONFIG_TRUNC_HMAC    << SSL_SERIALIZED_SESSION_CONFIG_TRUNC_HMAC_BIT    ) | \
         ( SSL_SERIALIZED_SESSION_CONFIG_ETM           << SSL_SERIALIZED_SESSION_CONFIG_ETM_BIT           ) | \
         ( SSL_SERIALIZED_SESSION_CONFIG_TICKET        << SSL_SERIALIZED_SESSION_CONFIG_TICKET_BIT        ) ) )
 
@@ -4532,44 +4527,61 @@
  * Serialize a session in the following format:
  * (in the presentation language of TLS, RFC 8446 section 3)
  *
- *  opaque mbedtls_version[3];   // major, minor, patch
- *  opaque session_format[2];    // version-specific 16-bit field determining
- *                               // the format of the remaining
- *                               // serialized data.
+ *  struct {
  *
- *  Note: When updating the format, remember to keep
- *        these version+format bytes.
+ *    opaque mbedtls_version[3];   // library version: major, minor, patch
+ *    opaque session_format[2];    // library-version specific 16-bit field
+ *                                 // determining the format of the remaining
+ *                                 // serialized data.
  *
- *                               // In this version, `session_format` determines
- *                               // the setting of those compile-time
- *                               // configuration options which influence
- *                               // the structure of mbedtls_ssl_session.
- *  uint64 start_time;
- *  uint8 ciphersuite[2];        // defined by the standard
- *  uint8 compression;           // 0 or 1
- *  uint8 session_id_len;        // at most 32
- *  opaque session_id[32];
- *  opaque master[48];           // fixed length in the standard
- *  uint32 verify_result;
- *  opaque peer_cert<0..2^24-1>; // length 0 means no peer cert
- *  opaque ticket<0..2^24-1>;    // length 0 means no ticket
- *  uint32 ticket_lifetime;
- *  uint8 mfl_code;              // up to 255 according to standard
- *  uint8 trunc_hmac;            // 0 or 1
- *  uint8 encrypt_then_mac;      // 0 or 1
+ *          Note: When updating the format, remember to keep
+ *          these version+format bytes.
  *
- * The order is the same as in the definition of the structure, except
- * verify_result is put before peer_cert so that all mandatory fields come
- * together in one block.
+ *                                 // In this version, `session_format` determines
+ *                                 // the setting of those compile-time
+ *                                 // configuration options which influence
+ *                                 // the structure of mbedtls_ssl_session.
+ *
+ *    uint8_t minor_ver;           // Protocol-version. Possible values:
+ *                                 // - TLS 1.2 (MBEDTLS_SSL_MINOR_VERSION_3)
+ *
+ *    select (serialized_session.minor_ver) {
+ *
+ *      case MBEDTLS_SSL_MINOR_VERSION_3: // TLS 1.2
+ *        serialized_session_tls12 data;
+ *
+ *   };
+ *
+ * } serialized_session;
+ *
  */
-static int ssl_session_save( const mbedtls_ssl_session *session,
-                             unsigned char omit_header,
-                             unsigned char *buf,
-                             size_t buf_len,
-                             size_t *olen )
+
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+/* Serialization of TLS 1.2 sessions:
+ *
+ * struct {
+ *    uint64 start_time;
+ *    uint8 ciphersuite[2];           // defined by the standard
+ *    uint8 compression;              // 0 or 1
+ *    uint8 session_id_len;           // at most 32
+ *    opaque session_id[32];
+ *    opaque master[48];              // fixed length in the standard
+ *    uint32 verify_result;
+ *    opaque peer_cert<0..2^24-1>;    // length 0 means no peer cert
+ *    opaque ticket<0..2^24-1>;       // length 0 means no ticket
+ *    uint32 ticket_lifetime;
+ *    uint8 mfl_code;                 // up to 255 according to standard
+ *    uint8 encrypt_then_mac;         // 0 or 1
+ * } serialized_session_tls12;
+ *
+ */
+static size_t ssl_session_save_tls12( const mbedtls_ssl_session *session,
+                                      unsigned char *buf,
+                                      size_t buf_len )
 {
     unsigned char *p = buf;
     size_t used = 0;
+
 #if defined(MBEDTLS_HAVE_TIME)
     uint64_t start;
 #endif
@@ -4579,23 +4591,6 @@
 #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
-
-    if( !omit_header )
-    {
-        /*
-         * Add version identifier
-         */
-
-        used += sizeof( ssl_serialized_session_header );
-
-        if( used <= buf_len )
-        {
-            memcpy( p, ssl_serialized_session_header,
-                    sizeof( ssl_serialized_session_header ) );
-            p += sizeof( ssl_serialized_session_header );
-        }
-    }
-
     /*
      * Time
      */
@@ -4738,9 +4733,61 @@
         *p++ = (unsigned char)( ( session->encrypt_then_mac ) & 0xFF );
 #endif
 
-    /* Done */
-    *olen = used;
+    return( used );
+}
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
 
+static int ssl_session_save( const mbedtls_ssl_session *session,
+                             unsigned char omit_header,
+                             unsigned char *buf,
+                             size_t buf_len,
+                             size_t *olen )
+{
+    unsigned char *p = buf;
+    size_t used = 0;
+
+    if( !omit_header )
+    {
+        /*
+         * Add Mbed TLS version identifier
+         */
+
+        used += sizeof( ssl_serialized_session_header );
+
+        if( used <= buf_len )
+        {
+            memcpy( p, ssl_serialized_session_header,
+                    sizeof( ssl_serialized_session_header ) );
+            p += sizeof( ssl_serialized_session_header );
+        }
+    }
+
+    /*
+     * TLS version identifier
+     */
+    used += 1;
+    if( used <= buf_len )
+    {
+        *p++ = session->minor_ver;
+    }
+
+    /* Forward to version-specific serialization routine. */
+    switch( session->minor_ver )
+    {
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    case MBEDTLS_SSL_MINOR_VERSION_3:
+    {
+        size_t remaining_len = used <= buf_len ? buf_len - used : 0;
+        used += ssl_session_save_tls12( session, p, remaining_len );
+        break;
+    }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+    default:
+        return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+    }
+
+    *olen = used;
     if( used > buf_len )
         return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
 
@@ -4764,13 +4811,10 @@
  * This internal version is wrapped by a public function that cleans up in
  * case of error, and has an extra option omit_header.
  */
-static int ssl_session_load( mbedtls_ssl_session *session,
-                             unsigned char omit_header,
-                             const unsigned char *buf,
-                             size_t len )
+static int ssl_session_load_tls12( mbedtls_ssl_session *session,
+                                   const unsigned char *buf,
+                                   size_t len )
 {
-    const unsigned char *p = buf;
-    const unsigned char * const end = buf + len;
 #if defined(MBEDTLS_HAVE_TIME)
     uint64_t start;
 #endif
@@ -4780,22 +4824,8 @@
 #endif /* MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
-    if( !omit_header )
-    {
-        /*
-         * Check version identifier
-         */
-
-        if( (size_t)( end - p ) < sizeof( ssl_serialized_session_header ) )
-            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
-
-        if( memcmp( p, ssl_serialized_session_header,
-                    sizeof( ssl_serialized_session_header ) ) != 0 )
-        {
-            return( MBEDTLS_ERR_SSL_VERSION_MISMATCH );
-        }
-        p += sizeof( ssl_serialized_session_header );
-    }
+    const unsigned char *p = buf;
+    const unsigned char * const end = buf + len;
 
     /*
      * Time
@@ -4980,6 +5010,54 @@
     return( 0 );
 }
 
+static int ssl_session_load( mbedtls_ssl_session *session,
+                             unsigned char omit_header,
+                             const unsigned char *buf,
+                             size_t len )
+{
+    const unsigned char *p = buf;
+    const unsigned char * const end = buf + len;
+
+    if( !omit_header )
+    {
+        /*
+         * Check Mbed TLS version identifier
+         */
+
+        if( (size_t)( end - p ) < sizeof( ssl_serialized_session_header ) )
+            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+
+        if( memcmp( p, ssl_serialized_session_header,
+                    sizeof( ssl_serialized_session_header ) ) != 0 )
+        {
+            return( MBEDTLS_ERR_SSL_VERSION_MISMATCH );
+        }
+        p += sizeof( ssl_serialized_session_header );
+    }
+
+    /*
+     * TLS version identifier
+     */
+    if( 1 > (size_t)( end - p ) )
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    session->minor_ver = *p++;
+
+    /* Dispatch according to TLS version. */
+    switch( session->minor_ver )
+    {
+#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
+    case MBEDTLS_SSL_MINOR_VERSION_3: /* TLS 1.2 */
+    {
+        size_t remaining_len = ( end - p );
+        return( ssl_session_load_tls12( session, p, remaining_len ) );
+    }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
+
+    default:
+        return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+    }
+}
+
 /*
  * Deserialize session: public wrapper for error cleaning
  */
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 081e8a4..72b0cdb 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -1435,13 +1435,14 @@
  * Populate a session structure for serialization tests.
  * Choose dummy values, mostly non-0 to distinguish from the init default.
  */
-static int ssl_populate_session( mbedtls_ssl_session *session,
-                                 int ticket_len,
-                                 const char *crt_file )
+static int ssl_populate_session_tls12( mbedtls_ssl_session *session,
+                                       int ticket_len,
+                                       const char *crt_file )
 {
 #if defined(MBEDTLS_HAVE_TIME)
     session->start = mbedtls_time( NULL ) - 42;
 #endif
+    session->minor_ver = MBEDTLS_SSL_MINOR_VERSION_3;
     session->ciphersuite = 0xabcd;
     session->compression = 1;
     session->id_len = sizeof( session->id );
@@ -1449,7 +1450,7 @@
     memset( session->master, 17, sizeof( session->master ) );
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C) && defined(MBEDTLS_FS_IO)
-    if( strlen( crt_file ) != 0 )
+    if( crt_file != NULL && strlen( crt_file ) != 0 )
     {
         mbedtls_x509_crt tmp_crt;
         int ret;
@@ -4005,7 +4006,7 @@
     mbedtls_ssl_session_init( &restored );
 
     /* Prepare a dummy session to work on */
-    TEST_ASSERT( ssl_populate_session( &original, ticket_len, crt_file ) == 0 );
+    TEST_ASSERT( ssl_populate_session_tls12( &original, ticket_len, crt_file ) == 0 );
 
     /* Serialize it */
     TEST_ASSERT( mbedtls_ssl_session_save( &original, NULL, 0, &len )
@@ -4023,6 +4024,7 @@
 #if defined(MBEDTLS_HAVE_TIME)
     TEST_ASSERT( original.start == restored.start );
 #endif
+    TEST_ASSERT( original.minor_ver == restored.minor_ver );
     TEST_ASSERT( original.ciphersuite == restored.ciphersuite );
     TEST_ASSERT( original.compression == restored.compression );
     TEST_ASSERT( original.id_len == restored.id_len );
@@ -4101,7 +4103,7 @@
     mbedtls_ssl_session_init( &session );
 
     /* Prepare a dummy session to work on */
-    TEST_ASSERT( ssl_populate_session( &session, ticket_len, crt_file ) == 0 );
+    TEST_ASSERT( ssl_populate_session_tls12( &session, ticket_len, crt_file ) == 0 );
 
     /* Get desired buffer size for serializing */
     TEST_ASSERT( mbedtls_ssl_session_save( &session, NULL, 0, &len0 )
@@ -4151,7 +4153,7 @@
     mbedtls_ssl_session_init( &session );
 
     /* Prepare dummy session and get serialized size */
-    TEST_ASSERT( ssl_populate_session( &session, ticket_len, crt_file ) == 0 );
+    TEST_ASSERT( ssl_populate_session_tls12( &session, ticket_len, crt_file ) == 0 );
     TEST_ASSERT( mbedtls_ssl_session_save( &session, NULL, 0, &good_len )
                  == MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
 
@@ -4187,7 +4189,7 @@
     mbedtls_ssl_session_init( &session );
 
     /* Prepare serialized session data */
-    TEST_ASSERT( ssl_populate_session( &session, ticket_len, crt_file ) == 0 );
+    TEST_ASSERT( ssl_populate_session_tls12( &session, ticket_len, crt_file ) == 0 );
     TEST_ASSERT( mbedtls_ssl_session_save( &session, NULL, 0, &good_len )
                  == MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
     TEST_ASSERT( ( good_buf = mbedtls_calloc( 1, good_len ) ) != NULL );
@@ -4232,6 +4234,7 @@
                                       corrupt_config == 1 };
 
     mbedtls_ssl_session_init( &session );
+    ssl_populate_session_tls12( &session, 0, NULL );
 
     /* Infer length of serialized session. */
     TEST_ASSERT( mbedtls_ssl_session_save( &session,