diff --git a/library/bignum_mod.h b/library/bignum_mod.h
index 6c283b3..ccf86c0 100644
--- a/library/bignum_mod.h
+++ b/library/bignum_mod.h
@@ -197,16 +197,12 @@
  *                  not be modified in any way until after
  *                  mbedtls_mpi_mod_modulus_free() is called.
  * \param p_limbs   The number of limbs of \p p.
- * \param int_rep   The internal representation to be used for residues
- *                  associated with \p N (see #mbedtls_mpi_mod_rep_selector).
  *
  * \return      \c 0 if successful.
- * \return      #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \p int_rep is invalid.
  */
 int mbedtls_mpi_mod_modulus_setup(mbedtls_mpi_mod_modulus *N,
                                   const mbedtls_mpi_uint *p,
-                                  size_t p_limbs,
-                                  mbedtls_mpi_mod_rep_selector int_rep);
+                                  size_t p_limbs);
 
 /** Setup an optimised-reduction compatible modulus structure.
  *