diff --git a/library/ssl_client.c b/library/ssl_client.c
index 20f1aff..e7453d5 100644
--- a/library/ssl_client.c
+++ b/library/ssl_client.c
@@ -432,7 +432,8 @@
 static int ssl_write_client_hello_body( mbedtls_ssl_context *ssl,
                                         unsigned char *buf,
                                         unsigned char *end,
-                                        size_t *out_len )
+                                        size_t *out_len,
+                                        size_t *binders_len )
 {
     int ret;
     mbedtls_ssl_handshake_params *handshake = ssl->handshake;
@@ -443,6 +444,7 @@
     int tls12_uses_ec = 0;
 
     *out_len = 0;
+    *binders_len = 0;
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
     unsigned char propose_tls12 =
@@ -641,6 +643,21 @@
     }
 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
 
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3) && \
+    defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+    /* The "pre_shared_key" extension (RFC 8446 Section 4.2.11)
+     * MUST be the last extension in the ClientHello.
+     */
+    if( propose_tls13 && mbedtls_ssl_conf_tls13_some_psk_enabled( ssl ) )
+    {
+        ret = mbedtls_ssl_tls13_write_identities_of_pre_shared_key_ext(
+                  ssl, p, end, &output_len, binders_len );
+        if( ret != 0 )
+            return( ret );
+        p += output_len;
+    }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3 && MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
     /* Write the length of the list of extensions. */
     extensions_len = p - p_extensions_len - 2;
 
@@ -837,7 +854,7 @@
 {
     int ret = 0;
     unsigned char *buf;
-    size_t buf_len, msg_len;
+    size_t buf_len, msg_len, binders_len;
 
     MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write client hello" ) );
 
@@ -849,7 +866,8 @@
 
     MBEDTLS_SSL_PROC_CHK( ssl_write_client_hello_body( ssl, buf,
                                                        buf + buf_len,
-                                                       &msg_len ) );
+                                                       &msg_len,
+                                                       &binders_len ) );
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2) && defined(MBEDTLS_SSL_PROTO_DTLS)
     if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
@@ -883,8 +901,22 @@
     else
 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 && MBEDTLS_SSL_PROTO_DTLS */
     {
-        mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_CLIENT_HELLO,
-                                            buf, msg_len );
+
+        mbedtls_ssl_add_hs_hdr_to_checksum( ssl, MBEDTLS_SSL_HS_CLIENT_HELLO,
+                                            msg_len );
+        ssl->handshake->update_checksum( ssl, buf, msg_len - binders_len );
+#if defined(MBEDTLS_SSL_PROTO_TLS1_3) && \
+    defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+        if( binders_len > 0 )
+        {
+            MBEDTLS_SSL_PROC_CHK(
+                mbedtls_ssl_tls13_write_binders_of_pre_shared_key_ext(
+                      ssl, buf + msg_len - binders_len, buf + msg_len ) );
+            ssl->handshake->update_checksum( ssl, buf + msg_len - binders_len,
+                                             binders_len );
+        }
+#endif /* MBEDTLS_SSL_PROTO_TLS1_3 && MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
         MBEDTLS_SSL_PROC_CHK( mbedtls_ssl_finish_handshake_msg( ssl,
                                                                 buf_len,
                                                                 msg_len ) );
diff --git a/library/ssl_misc.h b/library/ssl_misc.h
index d16b254..089b7d4 100644
--- a/library/ssl_misc.h
+++ b/library/ssl_misc.h
@@ -1349,6 +1349,10 @@
                                          unsigned char const *msg,
                                          size_t msg_len );
 
+void mbedtls_ssl_add_hs_hdr_to_checksum( mbedtls_ssl_context *ssl,
+                                         unsigned hs_type,
+                                         size_t total_hs_len );
+
 #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
 #if !defined(MBEDTLS_USE_PSA_CRYPTO)
 MBEDTLS_CHECK_RETURN_CRITICAL
@@ -2449,4 +2453,49 @@
                            unsigned char *obuf, size_t buf_len, size_t *olen );
 #endif
 
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+/* Check if we have any PSK to offer, returns 0 if PSK is available.
+ * Assign the psk and ticket if pointers are present.
+ */
+MBEDTLS_CHECK_RETURN_CRITICAL
+int mbedtls_ssl_get_psk_to_offer(
+        const mbedtls_ssl_context *ssl,
+        int *psk_type,
+        const unsigned char **psk, size_t *psk_len,
+        const unsigned char **psk_identity, size_t *psk_identity_len );
+
+/**
+ * \brief Given an SSL context and its associated configuration, write the TLS
+ *        1.3 specific Pre-Shared key extension.
+ *
+ * \param[in]   ssl     SSL context
+ * \param[in]   buf     Base address of the buffer where to write the extension
+ * \param[in]   end     End address of the buffer where to write the extension
+ * \param[out]  out_len Length in bytes of the Pre-Shared key extension: data
+ *                      written into the buffer \p buf by this function plus
+ *                      the length of the binders to be written.
+ * \param[out]  binders_len Length of the binders to be written at the end of
+ *                          the extension.
+ */
+MBEDTLS_CHECK_RETURN_CRITICAL
+int mbedtls_ssl_tls13_write_identities_of_pre_shared_key_ext(
+    mbedtls_ssl_context *ssl,
+    unsigned char *buf, unsigned char *end,
+    size_t *out_len, size_t *binders_len );
+
+/**
+ * \brief Given an SSL context and its associated configuration, write the TLS
+ *        1.3 specific Pre-Shared key extension binders at the end of the
+ *        ClientHello.
+ *
+ * \param[in]   ssl     SSL context
+ * \param[in]   buf     Base address of the buffer where to write the binders
+ * \param[in]   end     End address of the buffer where to write the binders
+ */
+MBEDTLS_CHECK_RETURN_CRITICAL
+int mbedtls_ssl_tls13_write_binders_of_pre_shared_key_ext(
+    mbedtls_ssl_context *ssl,
+    unsigned char *buf, unsigned char *end );
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
 #endif /* ssl_misc.h */
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 99768a2..6d91011 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -533,9 +533,9 @@
     }
 }
 
-static void mbedtls_ssl_add_hs_hdr_to_checksum( mbedtls_ssl_context *ssl,
-                                                unsigned hs_type,
-                                                size_t total_hs_len )
+void mbedtls_ssl_add_hs_hdr_to_checksum( mbedtls_ssl_context *ssl,
+                                         unsigned hs_type,
+                                         size_t total_hs_len )
 {
     unsigned char hs_hdr[4];
 
diff --git a/library/ssl_tls13_client.c b/library/ssl_tls13_client.c
index e38f117..cd3be46 100644
--- a/library/ssl_tls13_client.c
+++ b/library/ssl_tls13_client.c
@@ -595,6 +595,289 @@
     return( 0 );
 }
 
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+/*
+ * ssl_tls13_write_psk_key_exchange_modes_ext() structure:
+ *
+ * enum { psk_ke( 0 ), psk_dhe_ke( 1 ), ( 255 ) } PskKeyExchangeMode;
+ *
+ * struct {
+ *     PskKeyExchangeMode ke_modes<1..255>;
+ * } PskKeyExchangeModes;
+ */
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_tls13_write_psk_key_exchange_modes_ext( mbedtls_ssl_context *ssl,
+                                                       unsigned char *buf,
+                                                       unsigned char *end,
+                                                       size_t *out_len )
+{
+    unsigned char *p = buf;
+    int ke_modes_len = 0;
+
+    ((void) ke_modes_len );
+    *out_len = 0;
+
+    /* Skip writing extension if no PSK key exchange mode
+     * is enabled in the config.
+     */
+    if( !mbedtls_ssl_conf_tls13_some_psk_enabled( ssl ) )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip psk_key_exchange_modes extension" ) );
+        return( 0 );
+    }
+
+    /* Require 7 bytes of data, otherwise fail,
+     * even if extension might be shorter.
+     */
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 7 );
+    MBEDTLS_SSL_DEBUG_MSG(
+            3, ( "client hello, adding psk_key_exchange_modes extension" ) );
+
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES, p, 0 );
+
+    /* Skip extension length (2 bytes) and
+     * ke_modes length (1 byte) for now.
+     */
+    p += 5;
+
+    if( mbedtls_ssl_conf_tls13_psk_enabled( ssl ) )
+    {
+        *p++ = MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE;
+        ke_modes_len++;
+
+        MBEDTLS_SSL_DEBUG_MSG( 4, ( "Adding pure PSK key exchange mode" ) );
+    }
+
+    if( mbedtls_ssl_conf_tls13_psk_ephemeral_enabled( ssl ) )
+    {
+        *p++ = MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE;
+        ke_modes_len++;
+
+        MBEDTLS_SSL_DEBUG_MSG( 4, ( "Adding PSK-ECDHE key exchange mode" ) );
+    }
+
+    /* Now write the extension and ke_modes length */
+    MBEDTLS_PUT_UINT16_BE( ke_modes_len + 1, buf, 2 );
+    buf[4] = ke_modes_len;
+
+    *out_len = p - buf;
+    ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES;
+    return ( 0 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
+/*
+ * mbedtls_ssl_tls13_write_pre_shared_key_ext() structure:
+ *
+ * struct {
+ *   opaque identity<1..2^16-1>;
+ *   uint32 obfuscated_ticket_age;
+ * } PskIdentity;
+ *
+ * opaque PskBinderEntry<32..255>;
+ *
+ * struct {
+ *   PskIdentity identities<7..2^16-1>;
+ *   PskBinderEntry binders<33..2^16-1>;
+ * } OfferedPsks;
+ *
+ * struct {
+ *   select (Handshake.msg_type) {
+ *      case client_hello: OfferedPsks;
+ *      ...
+ *   };
+ * } PreSharedKeyExtension;
+ *
+ */
+
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+
+int mbedtls_ssl_tls13_write_identities_of_pre_shared_key_ext(
+    mbedtls_ssl_context *ssl,
+    unsigned char *buf, unsigned char *end,
+    size_t *out_len, size_t *binders_len )
+{
+    unsigned char *p = buf;
+    const unsigned char *psk;
+    size_t psk_len;
+    const unsigned char *psk_identity;
+    size_t psk_identity_len;
+    int psk_type;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info = NULL;
+    const int *ciphersuites;
+    psa_algorithm_t psa_hash_alg;
+    int hash_len = 0;
+    size_t identities_len, l_binders_len;
+    uint32_t obfuscated_ticket_age = 0;
+
+    *out_len = 0;
+    *binders_len = 0;
+
+    /* Check if we have any PSKs to offer. If so, return the first.
+     *
+     * NOTE: Ultimately, we want to be able to offer multiple PSKs,
+     *       in which case we want to iterate over them here.
+     *
+     * As it stands, however, we only ever offer one, chosen
+     * by the following heuristic:
+     * - If a ticket has been configured, offer the corresponding PSK.
+     * - If no ticket has been configured by an external PSK has been
+     *   configured, offer that.
+     * - Otherwise, skip the PSK extension.
+     */
+
+    if( mbedtls_ssl_get_psk_to_offer( ssl, &psk_type, &psk, &psk_len,
+                                      &psk_identity, &psk_identity_len ) != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip pre_shared_key extensions" ) );
+        return( 0 );
+    }
+
+    if( psk_type == MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL )
+    {
+        /*
+         * Ciphersuite list
+         */
+        ciphersuites = ssl->conf->ciphersuite_list;
+        for( int i = 0; ciphersuites[i] != 0; i++ )
+        {
+            ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(
+                                    ciphersuites[i] );
+
+            if( mbedtls_ssl_validate_ciphersuite(
+                                ssl, ciphersuite_info,
+                                MBEDTLS_SSL_VERSION_TLS1_3,
+                                MBEDTLS_SSL_VERSION_TLS1_3 ) != 0 )
+                continue;
+
+            /* In this implementation we only add one pre-shared-key
+             * extension.
+             */
+            ssl->session_negotiate->ciphersuite = ciphersuites[i];
+            break;
+        }
+    }
+
+    ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(
+            ssl->session_negotiate->ciphersuite );
+    /* No suitable ciphersuite for the PSK */
+    if( ciphersuite_info  == NULL )
+        return( 0 );
+
+    psa_hash_alg = mbedtls_psa_translate_md( ciphersuite_info->mac );
+    hash_len = PSA_HASH_LENGTH( psa_hash_alg );
+    if( hash_len == -1 )
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+
+    /* Check if we have space to write the extension, binder included.
+     * - extension_type         (2 bytes)
+     * - extension_data_len     (2 bytes)
+     * - identities_len         (2 bytes)
+     * - identity_len           (2 bytes)
+     * - identity               (psk_identity_len bytes)
+     * - obfuscated_ticket_age  (4 bytes)
+     * - binders_len            (2 bytes)
+     * - binder_len             (1 byte)
+     * - binder                 (hash_len bytes)
+     */
+
+    identities_len = 6 + psk_identity_len;
+    l_binders_len = 1 + hash_len;
+
+    MBEDTLS_SSL_DEBUG_MSG( 3,
+                 ( "client hello, adding pre_shared_key extension, "
+                   "omitting PSK binder list" ) );
+
+    /* Extension header */
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 8 );
+    MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_PRE_SHARED_KEY, p, 0 );
+    MBEDTLS_PUT_UINT16_BE( 2 + identities_len + 2 + l_binders_len , p, 2 );
+
+    MBEDTLS_PUT_UINT16_BE( identities_len, p, 4 );
+    MBEDTLS_PUT_UINT16_BE( psk_identity_len, p, 6 );
+    p += 8;
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, psk_identity_len );
+    memcpy( p, psk_identity, psk_identity_len );
+    p += psk_identity_len;
+
+    /* add obfuscated ticket age */
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 4 );
+    MBEDTLS_PUT_UINT32_BE( obfuscated_ticket_age, p, 0 );
+    p += 4;
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 + l_binders_len );
+    *out_len = ( p - buf ) + l_binders_len + 2;
+    *binders_len = l_binders_len + 2;
+
+    ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
+
+    return( 0 );
+}
+
+int mbedtls_ssl_tls13_write_binders_of_pre_shared_key_ext(
+    mbedtls_ssl_context *ssl,
+    unsigned char *buf, unsigned char *end )
+{
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
+    unsigned char *p = buf;
+    const unsigned char *psk_identity;
+    size_t psk_identity_len;
+    const mbedtls_ssl_ciphersuite_t *ciphersuite_info = NULL;
+    psa_algorithm_t psa_hash_alg;
+    int hash_len = 0;
+    const unsigned char *psk = NULL;
+    size_t psk_len = 0;
+    int psk_type;
+    unsigned char transcript[MBEDTLS_MD_MAX_SIZE];
+    size_t transcript_len;
+
+    if( mbedtls_ssl_get_psk_to_offer( ssl, &psk_type, &psk, &psk_len,
+                                      &psk_identity, &psk_identity_len ) != 0 )
+    {
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+    }
+
+    ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(
+            ssl->session_negotiate->ciphersuite );
+    if( ciphersuite_info  == NULL )
+        return( 0 );
+
+    psa_hash_alg = mbedtls_psa_translate_md( ciphersuite_info->mac );
+    hash_len = PSA_HASH_LENGTH( psa_hash_alg );
+    if( ( hash_len == -1 ) || ( ( end - buf ) != 3 + hash_len ) )
+        return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+
+    MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding PSK binder list" ) );
+
+    MBEDTLS_SSL_CHK_BUF_PTR( p, end, 3 + hash_len );
+    /* 2 bytes length field for array of psk binders */
+    MBEDTLS_PUT_UINT16_BE( hash_len + 1, p, 0 );
+    p += 2;
+
+    /* 1 bytes length field for next psk binder */
+    *p++ = MBEDTLS_BYTE_0( hash_len );
+
+    /* Get current state of handshake transcript. */
+    ret = mbedtls_ssl_get_handshake_transcript( ssl, ciphersuite_info->mac,
+                                                transcript, sizeof( transcript ),
+                                                &transcript_len );
+    if( ret != 0 )
+        return( ret );
+
+    ret = mbedtls_ssl_tls13_create_psk_binder( ssl,
+              mbedtls_psa_translate_md( ciphersuite_info->mac ),
+              psk, psk_len, psk_type,
+              transcript, p );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_tls13_create_psk_binder", ret );
+        return( ret );
+    }
+
+    return( 0 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
 int mbedtls_ssl_tls13_write_client_hello_exts( mbedtls_ssl_context *ssl,
                                                unsigned char *buf,
                                                unsigned char *end,
@@ -631,6 +914,22 @@
         p += ext_len;
     }
 
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+    /* For PSK-based key exchange we need the pre_shared_key extension
+     * and the psk_key_exchange_modes extension.
+     *
+     * The pre_shared_key extension MUST be the last extension in the
+     * ClientHello. Servers MUST check that it is the last extension and
+     * otherwise fail the handshake with an "illegal_parameter" alert.
+     *
+     * Add the psk_key_exchange_modes extension.
+     */
+    ret = ssl_tls13_write_psk_key_exchange_modes_ext( ssl, p, end, &ext_len );
+    if( ret != 0 )
+        return( ret );
+    p += ext_len;
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
     *out_len = p - buf;
 
     return( 0 );
@@ -929,6 +1228,92 @@
     return( 0 );
 }
 
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+/*
+ * struct {
+ *   opaque identity<1..2^16-1>;
+ *   uint32 obfuscated_ticket_age;
+ * } PskIdentity;
+ *
+ * opaque PskBinderEntry<32..255>;
+ *
+ * struct {
+ *
+ *   select (Handshake.msg_type) {
+ *         ...
+ *         case server_hello: uint16 selected_identity;
+ *   };
+ *
+ * } PreSharedKeyExtension;
+ *
+ */
+
+MBEDTLS_CHECK_RETURN_CRITICAL
+static int ssl_tls13_parse_server_pre_shared_key_ext( mbedtls_ssl_context *ssl,
+                                                      const unsigned char *buf,
+                                                      const unsigned char *end )
+{
+    int ret = 0;
+    size_t selected_identity;
+
+    const unsigned char *psk;
+    size_t psk_len;
+    const unsigned char *psk_identity;
+    size_t psk_identity_len;
+
+
+    /* Check which PSK we've offered.
+     *
+     * NOTE: Ultimately, we want to offer multiple PSKs, and in this
+     *       case, we need to iterate over them here.
+     */
+    if( mbedtls_ssl_get_psk_to_offer( ssl, NULL, &psk, &psk_len,
+                                      &psk_identity, &psk_identity_len ) != 0 )
+    {
+        /* If we haven't offered a PSK, the server must not send
+         * a PSK identity extension. */
+        return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
+    }
+
+    MBEDTLS_SSL_CHK_BUF_PTR( buf, end, 2 );
+    selected_identity = MBEDTLS_GET_UINT16_BE( buf, 0 );
+
+    /* We have offered only one PSK, so the only valid choice
+     * for the server is PSK index 0.
+     *
+     * This will change once we support multiple PSKs. */
+    if( selected_identity > 0 )
+    {
+        MBEDTLS_SSL_DEBUG_MSG( 1, ( "Server's chosen PSK identity out of range" ) );
+
+        if( ( ret = mbedtls_ssl_send_alert_message( ssl,
+                        MBEDTLS_SSL_ALERT_LEVEL_FATAL,
+                        MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER ) ) != 0 )
+        {
+            return( ret );
+        }
+
+        return( MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER );
+    }
+
+    /* Set the chosen PSK
+     *
+     * TODO: We don't have to do this in case we offered 0-RTT and the
+     *       server accepted it, because in this case we've already
+     *       set the handshake PSK. */
+    ret = mbedtls_ssl_set_hs_psk( ssl, psk, psk_len );
+    if( ret != 0 )
+    {
+        MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_set_hs_psk", ret );
+        return( ret );
+    }
+
+    ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PRE_SHARED_KEY;
+    return( 0 );
+}
+
+#endif
+
 /* Parse ServerHello message and configure context
  *
  * struct {
@@ -1139,12 +1524,24 @@
                     goto cleanup;
                 break;
 
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
             case MBEDTLS_TLS_EXT_PRE_SHARED_KEY:
-                MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension." ) );
-                MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key:Not supported yet" ) );
+                MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension" ) );
+                if( is_hrr )
+                {
+                    fatal_alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT;
+                    goto cleanup;
+                }
 
-                fatal_alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT;
-                goto cleanup;
+                if( ( ret = ssl_tls13_parse_server_pre_shared_key_ext(
+                                ssl, p, extension_data_end ) ) != 0 )
+                {
+                    MBEDTLS_SSL_DEBUG_RET(
+                        1, ( "ssl_tls13_parse_server_pre_shared_key_ext" ), ret );
+                    return( ret );
+                }
+                break;
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
 
             case MBEDTLS_TLS_EXT_KEY_SHARE:
                 MBEDTLS_SSL_DEBUG_MSG( 3, ( "found key_shares extension" ) );
diff --git a/library/ssl_tls13_generic.c b/library/ssl_tls13_generic.c
index 265d6d3..1e63c77 100644
--- a/library/ssl_tls13_generic.c
+++ b/library/ssl_tls13_generic.c
@@ -1505,4 +1505,41 @@
 }
 #endif /* MBEDTLS_ECDH_C */
 
+#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
+/* Check if we have any PSK to offer, returns 0 if PSK is available.
+ * Assign the psk and ticket if pointers are present.
+ */
+int mbedtls_ssl_get_psk_to_offer(
+        const mbedtls_ssl_context *ssl,
+        int *psk_type,
+        const unsigned char **psk, size_t *psk_len,
+        const unsigned char **psk_identity, size_t *psk_identity_len )
+{
+    int ptrs_present = 0;
+
+    if( psk_type != NULL && psk != NULL && psk_len != NULL &&
+        psk_identity != NULL && psk_identity_len != NULL )
+    {
+        ptrs_present = 1;
+    }
+
+    /* Check if an external PSK has been configured. */
+    if( ssl->conf->psk != NULL )
+    {
+        if( ptrs_present )
+        {
+            *psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL;
+            *psk = ssl->conf->psk;
+            *psk_len = ssl->conf->psk_len;
+            *psk_identity = ssl->conf->psk_identity;
+            *psk_identity_len = ssl->conf->psk_identity_len;
+        }
+
+        return( 0 );
+    }
+
+    return( 1 );
+}
+#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
+
 #endif /* MBEDTLS_SSL_TLS_C && MBEDTLS_SSL_PROTO_TLS1_3 */
diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 797b821..77e9f4e 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -11985,6 +11985,52 @@
             -s "parse ServerName extension" \
             -s "HTTP/1.0 200 OK"
 
+requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3
+requires_config_enabled MBEDTLS_SSL_SRV_C
+requires_config_enabled MBEDTLS_SSL_CLI_C
+run_test    "TLS 1.3, default suite, PSK" \
+            "$P_SRV nbio=2 debug_level=5 force_version=tls13 psk=010203 psk_identity=0a0b0c tls13_kex_modes=psk" \
+            "$P_CLI nbio=2 debug_level=5 force_version=tls13 psk=010203 psk_identity=0a0b0c tls13_kex_modes=psk" \
+            1 \
+            -c "=> write client hello" \
+            -c "client hello, adding pre_shared_key extension, omitting PSK binder list" \
+            -c "client hello, adding psk_key_exchange_modes extension" \
+            -c "client hello, adding PSK binder list" \
+            -c "<= write client hello"
+
+requires_openssl_tls1_3
+requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3
+requires_config_enabled MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE
+requires_config_enabled MBEDTLS_DEBUG_C
+requires_config_enabled MBEDTLS_SSL_CLI_C
+run_test    "TLS 1.3, default suite, PSK - openssl" \
+            "$O_NEXT_SRV -msg -debug -tls1_3 -psk_identity 0a0b0c -psk 010203 -allow_no_dhe_kex -nocert" \
+            "$P_CLI debug_level=4 psk=010203 psk_identity=0a0b0c tls13_kex_modes=psk" \
+            1 \
+            -c "=> write client hello" \
+            -c "client hello, adding pre_shared_key extension, omitting PSK binder list" \
+            -c "client hello, adding psk_key_exchange_modes extension" \
+            -c "client hello, adding PSK binder list" \
+            -c "<= write client hello"
+
+requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_3
+requires_gnutls_tls1_3
+requires_gnutls_next_no_ticket
+requires_config_enabled MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE
+requires_config_enabled MBEDTLS_DEBUG_C
+requires_config_enabled MBEDTLS_SSL_CLI_C
+run_test    "TLS 1.3, default suite, PSK - gnutls" \
+            "$G_NEXT_SRV -d 4 --priority=NORMAL:-VERS-ALL:+VERS-TLS1.3:+PSK:+CIPHER-ALL:%NO_TICKETS --pskhint=0a0b0c" \
+            "$P_CLI debug_level=4 psk=010203 psk_identity=0a0b0c tls13_kex_modes=psk" \
+            1 \
+            -c "=> write client hello" \
+            -c "client hello, adding pre_shared_key extension, omitting PSK binder list" \
+            -c "client hello, adding psk_key_exchange_modes extension" \
+            -c "client hello, adding PSK binder list" \
+            -s "Parsing extension 'PSK Key Exchange Modes/45'" \
+            -s "Parsing extension 'Pre Shared Key/41'" \
+            -c "<= write client hello"
+
 for i in opt-testcases/*.sh
 do
     TEST_SUITE_NAME=${i##*/}
@@ -12619,7 +12665,7 @@
 requires_config_enabled MBEDTLS_DEBUG_C
 requires_config_enabled MBEDTLS_SSL_CLI_C
 run_test    "TLS 1.3: NewSessionTicket: Basic check, m->G" \
-            "$G_NEXT_SRV --priority=NORMAL:-VERS-ALL:+VERS-TLS1.3:+CIPHER-ALL --disable-client-cert" \
+            "$G_NEXT_SRV --priority=NORMAL:-VERS-ALL:+VERS-TLS1.3:+CIPHER-ALL:+PSK --disable-client-cert" \
             "$P_CLI debug_level=4" \
             0 \
             -c "Protocol is TLSv1.3" \