diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 7273eb9..acb65e3 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -1365,6 +1365,7 @@
     }
 
     if (ret == 0) {
+        MBEDTLS_SSL_DEBUG_MSG(2, ("no supported_versions extension"));
         return SSL_CLIENT_HELLO_TLS1_2;
     }
 
@@ -1386,6 +1387,7 @@
          * the TLS version to negotiate.
          */
         if (MBEDTLS_SSL_VERSION_TLS1_2 == ret) {
+            MBEDTLS_SSL_DEBUG_MSG(2, ("supported_versions without 1.3"));
             return SSL_CLIENT_HELLO_TLS1_2;
         }
     }
@@ -1964,6 +1966,7 @@
         }
         ssl->keep_current_message = 1;
         ssl->tls_version = MBEDTLS_SSL_VERSION_TLS1_2;
+        MBEDTLS_SSL_DEBUG_MSG(1, ("non-1.3 ClientHello left for later processing"));
         return 0;
     }
 
diff --git a/tests/src/test_helpers/ssl_helpers.c b/tests/src/test_helpers/ssl_helpers.c
index 44e07ef..3c3bb6a 100644
--- a/tests/src/test_helpers/ssl_helpers.c
+++ b/tests/src/test_helpers/ssl_helpers.c
@@ -28,9 +28,22 @@
 {
     mbedtls_test_ssl_log_pattern *p = (mbedtls_test_ssl_log_pattern *) ctx;
 
+/* Change 0 to 1 for debugging of test cases that use this function. */
+#if 0
+    const char *q, *basename;
+    /* Extract basename from file */
+    for (q = basename = file; *q != '\0'; q++) {
+        if (*q == '/' || *q == '\\') {
+            basename = q + 1;
+        }
+    }
+    printf("%s:%04d: |%d| %s",
+           basename, line, level, str);
+#else
     (void) level;
     (void) line;
     (void) file;
+#endif
 
     if (NULL != p &&
         NULL != p->pattern &&
diff --git a/tests/suites/test_suite_ssl.data b/tests/suites/test_suite_ssl.data
index 565588b..18c5a41 100644
--- a/tests/suites/test_suite_ssl.data
+++ b/tests/suites/test_suite_ssl.data
@@ -3329,3 +3329,32 @@
 
 TLS 1.3 srv, max early data size, HRR, 98, wsz=49
 tls13_srv_max_early_data_size:TEST_EARLY_DATA_HRR:97:0
+
+# 1.2 minimal ClientHello breakdown:
+# 160303rlrl - record header, 2-byte record contents len
+# 01hlhlhl - handshake header, 3-byte handshake message len
+# 0303 - protocol version: 1.2
+# 0123456789abcdef (repeated, 4 times total) - 32-byte "random"
+# 00 - session ID (empty)
+# 0002cvcv - ciphersuite list: 2-byte len + list of 2-byte values (see below)
+# 0100 - compression methods: 1-byte len then "null" (only legal value now)
+# [then end, or extensions]
+# elel - 2-byte extensions length
+# ...
+#
+# Note: currently our TLS "1.3 or 1.2" code requires extension length to be
+# present even it it's 0. This is not strictly compliant but doesn't matter
+# much in practice as these days everyone wants to use signature_algorithms
+# (for hashes better than SHA-1), secure_renego (even if you have renego
+# disabled), and most people want either ECC or PSK related extensions.
+#
+# Note: cccc is currently not assigned, so can be used get a consistent
+# "no matching ciphersuite" behaviour regardless of the configuration.
+# 002f is MBEDTLS_TLS_RSA_WITH_AES_128_CBC_SHA, MTI in 1.2, but removed in 4.0.
+Inject ClientHello - TLS 1.2 good (for reference)
+depends_on:MBEDTLS_SSL_PROTO_TLS1_2:MBEDTLS_KEY_EXCHANGE_RSA_ENABLED:MBEDTLS_SSL_HAVE_AES:MBEDTLS_MD_CAN_SHA1:MBEDTLS_SSL_HAVE_CBC
+inject_client_content_on_the_wire:MBEDTLS_SSL_CLIENT_HELLO:"160303002f0100002b03030123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef000002002f01000000":"<= parse client hello":0
+
+Inject ClientHello - TLS 1.2 unknown ciphersuite (for reference)
+depends_on:MBEDTLS_SSL_PROTO_TLS1_2
+inject_client_content_on_the_wire:MBEDTLS_SSL_CLIENT_HELLO:"160303002f0100002b03030123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef000002cccc01000000":"got no ciphersuites in common":MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index e9584dc..9bdb023 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -5013,3 +5013,75 @@
     PSA_DONE();
 }
 /* END_CASE */
+
+/* BEGIN_CASE */
+void inject_client_content_on_the_wire(int state, data_t *hello, char *log_pattern,
+                                       int expected_ret)
+{
+    /* This function allows us to inject content at a specific state
+     * in the handshake, or when it's completed. The content is injected
+     * on the mock TCP socket, as if we were an active network attacker.
+     *
+     * This function is suitable to inject:
+     * - crafted records, at any point;
+     * - valid records that contain crafted handshake messages, but only
+     *   when the traffic is still unprotected (for TLS 1.2 that's most of the
+     *   handshake, for TLS 1.3 that's only the Hello messages);
+     * - handshake messages that are fragmented in a specific way,
+     *   under the same conditions as above.
+     */
+    enum { BUFFSIZE = 16384 };
+    mbedtls_test_ssl_endpoint server, client;
+    mbedtls_platform_zeroize(&server, sizeof(server));
+    mbedtls_platform_zeroize(&client, sizeof(client));
+    mbedtls_test_handshake_test_options options;
+    mbedtls_test_init_handshake_options(&options);
+    mbedtls_test_ssl_log_pattern srv_pattern;
+    memset(&srv_pattern, 0, sizeof(srv_pattern));
+    int ret = -1;
+
+    PSA_INIT();
+
+    srv_pattern.pattern = log_pattern;
+    options.srv_log_obj = &srv_pattern;
+    options.srv_log_fun = mbedtls_test_ssl_log_analyzer;
+    mbedtls_debug_set_threshold(3);
+
+    ret = mbedtls_test_ssl_endpoint_init(&server, MBEDTLS_SSL_IS_SERVER,
+                                         &options, NULL, NULL, NULL);
+    TEST_EQUAL(ret,  0);
+
+    ret = mbedtls_test_ssl_endpoint_init(&client, MBEDTLS_SSL_IS_CLIENT,
+                                         &options, NULL, NULL, NULL);
+    TEST_EQUAL(ret,  0);
+
+    ret = mbedtls_test_mock_socket_connect(&server.socket, &client.socket,
+                                           BUFFSIZE);
+    TEST_EQUAL(ret,  0);
+
+    /* Make the server move to the required state */
+    ret = mbedtls_test_move_handshake_to_state(&client.ssl, &server.ssl, state);
+    TEST_EQUAL(ret, 0);
+
+    /* Send the crafted message */
+    ret = mbedtls_test_mock_tcp_send_b(&client.socket, hello->x, hello->len);
+    TEST_ASSERT(ret >= 0 && (size_t) ret == hello->len);
+
+    /* Have the server process it.
+     * Need the loop because a server that support 1.3 and 1.2
+     * will process a 1.2 ClientHello in two steps.
+     */
+    do {
+        ret = mbedtls_ssl_handshake_step(&server.ssl);
+    } while (ret == 0 && server.ssl.state == state);
+    TEST_EQUAL(ret,  expected_ret);
+    TEST_EQUAL(srv_pattern.counter, 1);
+
+exit:
+    mbedtls_test_free_handshake_options(&options);
+    mbedtls_test_ssl_endpoint_free(&server, NULL);
+    mbedtls_test_ssl_endpoint_free(&client, NULL);
+    mbedtls_debug_set_threshold(0);
+    PSA_DONE();
+}
+/* END_CASE */