diff --git a/ortools/flatzinc/checker.cc b/ortools/flatzinc/checker.cc
index 34ab1e4fe7..dcf82e94af 100644
--- a/ortools/flatzinc/checker.cc
+++ b/ortools/flatzinc/checker.cc
@@ -1072,8 +1072,8 @@ bool CheckSetNotIn(const Constraint& ct,
 bool CheckSetInReif(const Constraint& ct,
                     const std::function<int64_t(Variable*)>& evaluator) {
   const int64_t value = Eval(ct.arguments[0], evaluator);
-  const bool status = Eval(ct.arguments[2], evaluator);
-  return status == ct.arguments[1].Contains(value) != 0;
+  const bool status = Eval(ct.arguments[2], evaluator) != 0;
+  return status == ct.arguments[1].Contains(value);
 }
 
 bool CheckSlidingSum(const Constraint& ct,