diff --git a/include/mbedtls/mbedtls_config.h b/include/mbedtls/mbedtls_config.h
index 3300f5f..e16f31a 100644
--- a/include/mbedtls/mbedtls_config.h
+++ b/include/mbedtls/mbedtls_config.h
@@ -2130,6 +2130,10 @@
  * before calling any function from the SSL/TLS, X.509 or PK modules, except
  * for the various mbedtls_xxx_init() functions which can be called at any time.
  *
+ * \warning In multithreaded applications, you must also enable
+ * #MBEDTLS_THREADING_C, unless only one thread ever calls PSA functions
+ * (`psa_xxx()`), including indirect calls through SSL/TLS, X.509 or PK.
+ *
  * \note An important and desirable effect of this option is that it allows
  * PK, X.509 and TLS to take advantage of PSA drivers. For example, enabling
  * this option is what allows use of drivers for ECDSA, ECDH and EC J-PAKE in
@@ -2139,10 +2143,6 @@
  *
  * \note See docs/use-psa-crypto.md for a complete description this option.
  *
- * \note In multithreaded applications, you must also enable
- *       #MBEDTLS_THREADING_C, unless only one thread ever calls
- *       `psa_xxx()`, PK, X.509 or TLS functions.
- *
  * Requires: MBEDTLS_PSA_CRYPTO_C.
  *
  * Uncomment this to enable internal use of PSA Crypto and new associated APIs.
@@ -3224,6 +3224,14 @@
  *
  * \note In multithreaded applications, you must enable #MBEDTLS_THREADING_C,
  *       unless only one thread ever calls `psa_xxx()` functions.
+ *       That includes indirect calls, such as:
+ *       - performing a TLS handshake if support for TLS 1.3 is enabled;
+ *       - using a TLS 1.3 connection;
+ *       - indirect calls from PK, X.509 or SSL functions when
+ *         #MBEDTLS_USE_PSA_CRYPTO is enabled;
+ *       - indirect calls to calculate a hash when #MBEDTLS_MD_C is disabled;
+ *       - any other call to a function that requires calling psa_crypto_init()
+ *         beforehand.
  *
  * Module:  library/psa_crypto.c
  *
@@ -3662,12 +3670,17 @@
  *   if `MBEDTLS_USE_PSA_CRYPTO` is enabled (regardless of whether individual
  *   TLS, X.509 or PK contexts are shared between threads).
  * - A TLS 1.3 connection, regardless of the compile-time configuration.
- * - Any library feature that calculates a hash, except for algorithm-specific
- *   low-level modules, if `MBEDTLS_MD_C` is disabled.
- * - Any library feature that calculates a hash, except for algorithm-specific
- *   low-level modules, if `MBEDTLS_CIPHER_C` is disabled.
+ * - Any library feature that calculates a hash, if `MBEDTLS_MD_C` is disabled.
+ *   As an exception, algorithm-specific low-level modules do not require
+ *   threading protection unless the contexts are shared between threads.
+ * - Any library feature that performs symmetric encryption or decryption,
+ *   if `MBEDTLS_CIPHER_C` is disabled.
+ *   As an exception, algorithm-specific low-level modules do not require
+ *   threading protection unless the contexts are shared between threads.
  * - Any use of a cryptographic context if the same context is used in
  *   multiple threads.
+ * - Any call to a function where the documentation specifies that
+ *   psa_crypto_init() must be called prior to that function.
  *
  * See also our Knowledge Base article about threading:
  * https://mbed-tls.readthedocs.io/en/latest/kb/development/thread-safety-and-multi-threading