diff --git a/include/mbedtls/bignum.h b/include/mbedtls/bignum.h
index 0ee32dd..40cfab4 100644
--- a/include/mbedtls/bignum.h
+++ b/include/mbedtls/bignum.h
@@ -725,10 +725,19 @@
  */
 int mbedtls_mpi_inv_mod( mbedtls_mpi *X, const mbedtls_mpi *A, const mbedtls_mpi *N );
 
+#if !defined(MBEDTLS_DEPRECATED_REMOVED)
+#if defined(MBEDTLS_DEPRECATED_WARNING)
+#define MBEDTLS_DEPRECATED      __attribute__((deprecated))
+#else
+#define MBEDTLS_DEPRECATED
+#endif
 /**
  * \brief          Miller-Rabin primality test with error probability of
  *                 2<sup>-80</sup>
  *
+ * \deprecated     Superseded by mbedtls_mpi_is_prime_ext() which allows
+ *                 specifying the number of Miller-Rabin rounds.
+ *
  * \param X        MPI to check
  * \param f_rng    RNG function
  * \param p_rng    RNG parameter
@@ -737,11 +746,39 @@
  *                 MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed,
  *                 MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if X is not prime
  */
-int mbedtls_mpi_is_prime( const mbedtls_mpi *X,
-                  int (*f_rng)(void *, unsigned char *, size_t),
-                  void *p_rng );
+MBEDTLS_DEPRECATED int mbedtls_mpi_is_prime( const mbedtls_mpi *X,
+                          int (*f_rng)(void *, unsigned char *, size_t),
+                          void *p_rng );
+#undef MBEDTLS_DEPRECATED
+#endif /* !MBEDTLS_DEPRECATED_REMOVED */
 
 /**
+ * \brief          Miller-Rabin primality test.
+ *
+ * \warning        If \p X is potentially generated by an adversary, for example
+ *                 when validating cryptographic parameters that you didn't
+ *                 generate yourself and that are supposed to be prime, then
+ *                 \p rounds should be at least the half of the security
+ *                 strength of the cryptographic algorithm. On the other hand,
+ *                 if \p X is chosen uniformly or non-adversially (as is the
+ *                 case when mbedtls_mpi_gen_prime calls this function), then
+ *                 \p rounds can be much lower.
+ *
+ * \param X        MPI to check
+ * \param rounds   Number of bases to perform Miller-Rabin primality test for.
+ *                 The probability of returning 0 on a composite is at most
+ *                 2<sup>-2*\p rounds</sup>.
+ * \param f_rng    RNG function
+ * \param p_rng    RNG parameter
+ *
+ * \return         0 if successful (probably prime),
+ *                 MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed,
+ *                 MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if X is not prime
+ */
+int mbedtls_mpi_is_prime_ext( const mbedtls_mpi *X, int rounds,
+                              int (*f_rng)(void *, unsigned char *, size_t),
+                              void *p_rng );
+/**
  * \brief Flags for mbedtls_mpi_gen_prime()
  *
  * Each of these flags is a constraint on the result X returned by