diff --git a/library/bignum_mod_raw.h b/library/bignum_mod_raw.h
index 00ec921..bdd2ead 100644
--- a/library/bignum_mod_raw.h
+++ b/library/bignum_mod_raw.h
@@ -51,16 +51,11 @@
  * \warning        If \p assign is neither 0 nor 1, the result of this function
  *                 is indeterminate, and the resulting value in \p X might be
  *                 neither its original value nor the value in \p Y.
- *
- * \return         \c 0 if successful.
- * \return         #MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL if \p X isn't
- *                 large enough to hold the value in \p Y.
- * \return         #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \p X or \p Y is invalid.
  */
-int mbedtls_mpi_mod_raw_cond_assign( mbedtls_mpi_uint *X,
-                                     mbedtls_mpi_uint *Y,
-                                     const mbedtls_mpi_mod_modulus *m,
-                                     unsigned char assign );
+void mbedtls_mpi_mod_raw_cond_assign( mbedtls_mpi_uint *X,
+                                      mbedtls_mpi_uint *Y,
+                                      const mbedtls_mpi_mod_modulus *m,
+                                      unsigned char assign );
 
 /**
  * \brief   Perform a safe conditional copy of MPI which doesn't reveal whether
@@ -80,15 +75,11 @@
  * \warning        If \p swap is neither 0 nor 1, the result of this function
  *                 is indeterminate, and both \p X and \p Y might end up with
  *                 values different to either of the original ones.
- *
- * \return         \c 0 if successful.
- * \return         #MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL if the size of
- *                 \p X and \p Y is differ.
- * \return         #MBEDTLS_ERR_MPI_BAD_INPUT_DATA if \p X or \p Y is invalid.
- */int mbedtls_mpi_mod_raw_cond_swap( mbedtls_mpi_uint *X,
-                                   mbedtls_mpi_uint *Y,
-                                   const mbedtls_mpi_mod_modulus *m,
-                                   unsigned char swap );
+ */
+void mbedtls_mpi_mod_raw_cond_swap( mbedtls_mpi_uint *X,
+                                    mbedtls_mpi_uint *Y,
+                                    const mbedtls_mpi_mod_modulus *m,
+                                    unsigned char swap );
 
 /** Import X from unsigned binary data.
  *