From 746dd745ad373c7b304b8e87f432b7f258ee06b8 Mon Sep 17 00:00:00 2001
From: Nikolaj Bjorner <nbjorner@microsoft.com>
Date: Sun, 6 Dec 2020 14:06:08 -0800
Subject: [PATCH] fix #4856

---
 src/smt/watch_list.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/smt/watch_list.cpp b/src/smt/watch_list.cpp
index 5cb28a312..973e586fa 100644
--- a/src/smt/watch_list.cpp
+++ b/src/smt/watch_list.cpp
@@ -106,7 +106,8 @@ namespace smt {
             else 
                 *prev++ = *it;
         }
-        end_cls_core() -= num_deleted * sizeof(clause *);
+        if (num_deleted > 0)
+            end_cls_core() -= num_deleted * sizeof(clause *);
     }
     
     void watch_list::remove_literal(literal l) {