diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 8c1e372..9fabda4 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -8942,6 +8942,7 @@
  *
  * struct {
  *    uint64 start_time;
+ *    uint8 endpoint;
  *    uint8 ciphersuite[2];           // defined by the standard
  *    uint8 session_id_len;           // at most 32
  *    opaque session_id[32];
@@ -8988,13 +8989,15 @@
     /*
      * Basic mandatory fields
      */
-    used += 2   /* ciphersuite */
+    used += 1   /* endpoint */
+            + 2 /* ciphersuite */
             + 1 /* id_len */
             + sizeof(session->id)
             + sizeof(session->master)
             + 4; /* verify_result */
 
     if (used <= buf_len) {
+        *p++ = session->endpoint;
         MBEDTLS_PUT_UINT16_BE(session->ciphersuite, p, 0);
         p += 2;
 
@@ -9129,10 +9132,11 @@
     /*
      * Basic mandatory fields
      */
-    if (2 + 1 + 32 + 48 + 4 > (size_t) (end - p)) {
+    if (1 + 2 + 1 + 32 + 48 + 4 > (size_t) (end - p)) {
         return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
     }
 
+    session->endpoint = *p++;
     session->ciphersuite = MBEDTLS_GET_UINT16_BE(p, 0);
     p += 2;
 
diff --git a/tests/include/test/ssl_helpers.h b/tests/include/test/ssl_helpers.h
index d03c624..ec00fd5 100644
--- a/tests/include/test/ssl_helpers.h
+++ b/tests/include/test/ssl_helpers.h
@@ -531,6 +531,7 @@
  */
 int mbedtls_test_ssl_tls12_populate_session(mbedtls_ssl_session *session,
                                             int ticket_len,
+                                            int endpoint_type,
                                             const char *crt_file);
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
diff --git a/tests/src/test_helpers/ssl_helpers.c b/tests/src/test_helpers/ssl_helpers.c
index 3d8937d..8f20fa6 100644
--- a/tests/src/test_helpers/ssl_helpers.c
+++ b/tests/src/test_helpers/ssl_helpers.c
@@ -1636,12 +1636,15 @@
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
 int mbedtls_test_ssl_tls12_populate_session(mbedtls_ssl_session *session,
                                             int ticket_len,
+                                            int endpoint_type,
                                             const char *crt_file)
 {
 #if defined(MBEDTLS_HAVE_TIME)
     session->start = mbedtls_time(NULL) - 42;
 #endif
     session->tls_version = MBEDTLS_SSL_VERSION_TLS1_2;
+    session->endpoint = endpoint_type == MBEDTLS_SSL_IS_CLIENT ?
+                        MBEDTLS_SSL_IS_CLIENT : MBEDTLS_SSL_IS_SERVER;
     session->ciphersuite = 0xabcd;
     session->id_len = sizeof(session->id);
     memset(session->id, 66, session->id_len);
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 8a03d1b..b116705 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -1941,7 +1941,6 @@
     USE_PSA_INIT();
 
     /* Prepare a dummy session to work on */
-    ((void) endpoint_type);
     ((void) tls_version);
     ((void) ticket_len);
     ((void) crt_file);
@@ -1955,7 +1954,7 @@
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
     if (tls_version == MBEDTLS_SSL_VERSION_TLS1_2) {
         TEST_ASSERT(mbedtls_test_ssl_tls12_populate_session(
-                        &original, ticket_len, crt_file) == 0);
+                        &original, ticket_len, endpoint_type, crt_file) == 0);
     }
 #endif
 
@@ -1995,6 +1994,7 @@
 #endif
 
     TEST_ASSERT(original.tls_version == restored.tls_version);
+    TEST_ASSERT(original.endpoint == restored.endpoint);
     TEST_ASSERT(original.ciphersuite == restored.ciphersuite);
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
     if (tls_version == MBEDTLS_SSL_VERSION_TLS1_2) {
@@ -2053,7 +2053,6 @@
 
 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
     if (tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
-        TEST_ASSERT(original.endpoint == restored.endpoint);
         TEST_ASSERT(original.ciphersuite == restored.ciphersuite);
         TEST_ASSERT(original.ticket_age_add == restored.ticket_age_add);
         TEST_ASSERT(original.ticket_flags == restored.ticket_flags);
@@ -2123,7 +2122,6 @@
     USE_PSA_INIT();
 
     /* Prepare a dummy session to work on */
-    ((void) endpoint_type);
     ((void) ticket_len);
     ((void) crt_file);
 
@@ -2138,7 +2136,7 @@
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
         case MBEDTLS_SSL_VERSION_TLS1_2:
             TEST_ASSERT(mbedtls_test_ssl_tls12_populate_session(
-                            &session, ticket_len, crt_file) == 0);
+                            &session, ticket_len, endpoint_type, crt_file) == 0);
             break;
 #endif
         default:
@@ -2197,7 +2195,6 @@
     USE_PSA_INIT();
 
     /* Prepare dummy session and get serialized size */
-    ((void) endpoint_type);
     ((void) ticket_len);
     ((void) crt_file);
 
@@ -2211,7 +2208,7 @@
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
         case MBEDTLS_SSL_VERSION_TLS1_2:
             TEST_ASSERT(mbedtls_test_ssl_tls12_populate_session(
-                            &session, ticket_len, crt_file) == 0);
+                            &session, ticket_len, endpoint_type, crt_file) == 0);
             break;
 #endif
         default:
@@ -2257,7 +2254,6 @@
     USE_PSA_INIT();
 
     /* Prepare serialized session data */
-    ((void) endpoint_type);
     ((void) ticket_len);
     ((void) crt_file);
 
@@ -2272,7 +2268,7 @@
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
         case MBEDTLS_SSL_VERSION_TLS1_2:
             TEST_ASSERT(mbedtls_test_ssl_tls12_populate_session(
-                            &session, ticket_len, crt_file) == 0);
+                            &session, ticket_len, endpoint_type, crt_file) == 0);
             break;
 #endif
 
@@ -2329,7 +2325,6 @@
 
     mbedtls_ssl_session_init(&session);
     USE_PSA_INIT();
-    ((void) endpoint_type);
 
     switch (tls_version) {
 #if defined(MBEDTLS_SSL_PROTO_TLS1_3)
@@ -2341,7 +2336,7 @@
 #if defined(MBEDTLS_SSL_PROTO_TLS1_2)
         case MBEDTLS_SSL_VERSION_TLS1_2:
             TEST_ASSERT(mbedtls_test_ssl_tls12_populate_session(
-                            &session, 0, NULL) == 0);
+                            &session, 0, endpoint_type, NULL) == 0);
 
             break;
 #endif