diff --git a/lib/krb5/store.c b/lib/krb5/store.c
index 74c0fd281..2cb42c9a0 100644
--- a/lib/krb5/store.c
+++ b/lib/krb5/store.c
@@ -412,7 +412,7 @@ krb5_store_int(krb5_storage *sp,
 	return EINVAL;
 
     if (BYTEORDER_IS_PACKED(sp)) {
-        size_t mask = ~0ULL >> (64 - len * 8);
+        uint64_t mask = ~0ULL >> (64 - len * 8);
         value &= mask;
         p += sizeof(v) - 1;
         len = pack_int(p, value);