diff --git a/library/bignum_mod_raw.c b/library/bignum_mod_raw.c
index 01f5a44..94dcf77 100644
--- a/library/bignum_mod_raw.c
+++ b/library/bignum_mod_raw.c
@@ -120,11 +120,11 @@
 
 /* BEGIN MERGE SLOT 5 */
 void mbedtls_mpi_mod_raw_add( mbedtls_mpi_uint *X,
-                              mbedtls_mpi_uint const *A,
-                              mbedtls_mpi_uint const *B,
+                              const mbedtls_mpi_uint *A,
+                              const mbedtls_mpi_uint *B,
                               const mbedtls_mpi_mod_modulus *N )
 {
-    size_t carry, borrow = 0;
+    mbedtls_mpi_uint carry, borrow;
     carry  = mbedtls_mpi_core_add( X, A, B, N->limbs );
     borrow = mbedtls_mpi_core_sub( X, X, N->p, N->limbs );
     (void) mbedtls_mpi_core_add_if( X, N->p, N->limbs, ( carry < borrow ) );