diff --git a/lib/sfrsd2/sfrsd_paper/binomial_subs.c b/lib/sfrsd2/sfrsd_paper/binomial_subs.c
index 139488b2f..be4a0ae5f 100644
--- a/lib/sfrsd2/sfrsd_paper/binomial_subs.c
+++ b/lib/sfrsd2/sfrsd_paper/binomial_subs.c
@@ -23,11 +23,11 @@ unsigned long long binomial(unsigned long long n, unsigned long long k) {
   if (k >= n) return (k == n);
   if (k > n/2) k = n-k;
   for (d = 1; d <= k; d++) {
-    if (r >= ULONG_LONG_MAX/n) {  /* Possible overflow */
+    if (r >= ULLONG_MAX/n) {  /* Possible overflow */
       unsigned long long nr, dr;  /* reduced numerator / denominator */
       g = gcd_ui(n, d);  nr = n/g;  dr = d/g;
       g = gcd_ui(r, dr);  r = r/g;  dr = dr/g;
-      if (r >= ULONG_LONG_MAX/nr) return 0;  /* Unavoidable overflow */
+      if (r >= ULLONG_MAX/nr) return 0;  /* Unavoidable overflow */
       r *= nr;
       r /= dr;
       n--;