diff --git a/ctaocrypt/src/integer.c b/ctaocrypt/src/integer.c
index 32da4f612..f5f6a91e6 100644
--- a/ctaocrypt/src/integer.c
+++ b/ctaocrypt/src/integer.c
@@ -3400,7 +3400,7 @@ int mp_reduce (mp_int * x, mp_int * m, mp_int * mu)
   mp_rshd (&q, um - 1);         
 
   /* according to HAC this optimization is ok */
-  if (((unsigned long) um) > (((mp_digit)1) << (DIGIT_BIT - 1))) {
+  if (((mp_word) um) > (((mp_digit)1) << (DIGIT_BIT - 1))) {
     if ((res = mp_mul (&q, mu, &q)) != MP_OKAY) {
       goto CLEANUP;
     }