diff --git a/include/mbedtls/psa_util.h b/include/mbedtls/psa_util.h
index 984f031..f79178d 100644
--- a/include/mbedtls/psa_util.h
+++ b/include/mbedtls/psa_util.h
@@ -23,42 +23,22 @@
 
 #if defined(MBEDTLS_PSA_CRYPTO_C)
 
-/* Expose whatever RNG the PSA subsystem uses to applications using the
- * mbedtls_xxx API. The declarations and definitions here need to be
- * consistent with the implementation in library/psa_crypto_random_impl.h.
- * See that file for implementation documentation. */
-
-
-/* The type of a `f_rng` random generator function that many library functions
- * take.
- *
- * This type name is not part of the Mbed TLS stable API. It may be renamed
- * or moved without warning.
- */
-typedef int mbedtls_f_rng_t(void *p_rng, unsigned char *output, size_t output_size);
-
-#if defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG)
-
 /** The random generator function for the PSA subsystem.
  *
  * This function is suitable as the `f_rng` random generator function
- * parameter of many `mbedtls_xxx` functions. Use #MBEDTLS_PSA_RANDOM_STATE
- * to obtain the \p p_rng parameter.
+ * parameter of many `mbedtls_xxx` functions.
  *
  * The implementation of this function depends on the configuration of the
  * library.
  *
- * \note Depending on the configuration, this may be a function or
- *       a pointer to a function.
- *
  * \note This function may only be used if the PSA crypto subsystem is active.
  *       This means that you must call psa_crypto_init() before any call to
  *       this function, and you must not call this function after calling
  *       mbedtls_psa_crypto_free().
  *
- * \param p_rng         The random generator context. This must be
- *                      #MBEDTLS_PSA_RANDOM_STATE. No other state is
- *                      supported.
+ * \param p_rng         This parameter is only kept for backward compatibility
+ *                      reasons with legacy `f_rng` functions and it's ignored.
+ *                      Set to #MBEDTLS_PSA_RANDOM_STATE or NULL.
  * \param output        The buffer to fill. It must have room for
  *                      \c output_size bytes.
  * \param output_size   The number of bytes to write to \p output.
@@ -80,32 +60,11 @@
 
 /** The random generator state for the PSA subsystem.
  *
- * This macro expands to an expression which is suitable as the `p_rng`
- * random generator state parameter of many `mbedtls_xxx` functions.
- * It must be used in combination with the random generator function
- * mbedtls_psa_get_random().
- *
- * The implementation of this macro depends on the configuration of the
- * library. Do not make any assumption on its nature.
+ * This macro always expands to NULL because the `p_rng` parameter is unused
+ * in mbedtls_psa_get_random(), but it's kept for interface's backward
+ * compatibility.
  */
-#define MBEDTLS_PSA_RANDOM_STATE NULL
-
-#else /* !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) */
-
-#if defined(MBEDTLS_CTR_DRBG_C)
-#include "mbedtls/ctr_drbg.h"
-typedef mbedtls_ctr_drbg_context mbedtls_psa_drbg_context_t;
-static mbedtls_f_rng_t *const mbedtls_psa_get_random = mbedtls_ctr_drbg_random;
-#elif defined(MBEDTLS_HMAC_DRBG_C)
-#include "mbedtls/hmac_drbg.h"
-typedef mbedtls_hmac_drbg_context mbedtls_psa_drbg_context_t;
-static mbedtls_f_rng_t *const mbedtls_psa_get_random = mbedtls_hmac_drbg_random;
-#endif
-extern mbedtls_psa_drbg_context_t *const mbedtls_psa_random_state;
-
-#define MBEDTLS_PSA_RANDOM_STATE mbedtls_psa_random_state
-
-#endif /* !defined(MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG) */
+#define MBEDTLS_PSA_RANDOM_STATE    NULL
 
 /** \defgroup psa_tls_helpers TLS helper functions
  * @{