From 308e43e56aee98940d5e60f3da2cb5b0cf76b822 Mon Sep 17 00:00:00 2001
From: Weijia Wang <9713184+wegank@users.noreply.github.com>
Date: Mon, 15 Dec 2025 13:22:00 +0100
Subject: [PATCH] Fixes a UB on shifts during root refinement

---
 src/usolve/refine.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/usolve/refine.c b/src/usolve/refine.c
index d07759bc..14e917a9 100644
--- a/src/usolve/refine.c
+++ b/src/usolve/refine.c
@@ -287,7 +287,7 @@ static void refine_root_by_N_positive_k(mpz_t *upol, unsigned long int *deg_ptr,
 
   mpz_set(*vala, *tmpvala);
   mpz_set(*valb, *tmpvalb);
-  int64_t maxindex = (1L<<(Nlog));
+  int64_t maxindex = (Nlog >= 64) ? 1 : (INT64_C(1) << Nlog);
 
   if(index == -2 || index == 0 || (LOG2(index) > Nlog && index > 0) ){
     if(Nlog == 2) index = 2;