diff --git a/src/arith/int_set.cc b/src/arith/int_set.cc
index 7d601d9a8baec..a75d316a7ece4 100644
--- a/src/arith/int_set.cc
+++ b/src/arith/int_set.cc
@@ -865,6 +865,7 @@ IntSet UnionLowerBound(const Array<IntSet>& sets) {
   PrimExpr min_inclusive{nullptr};
   PrimExpr max_inclusive(nullptr);
   for (const IntSet& int_set : sets) {
+    if (int_set.IsNothing()) continue;
     if (const auto* interval_set = int_set.as<IntervalSetNode>()) {
       PrimExpr new_min_inclusive = interval_set->min_value;
       PrimExpr new_max_inclusive = interval_set->max_value;
diff --git a/tests/python/unittest/test_arith_intset.py b/tests/python/unittest/test_arith_intset.py
index da3fd94f8192b..a6c7390782a9f 100644
--- a/tests/python/unittest/test_arith_intset.py
+++ b/tests/python/unittest/test_arith_intset.py
@@ -370,7 +370,8 @@ def test_union_lower_bound():
     pos_inf = tvm.arith.int_set.pos_inf()
     set_0 = tvm.arith.IntervalSet(min_value=neg_inf, max_value=0)
     set_1 = tvm.arith.IntervalSet(min_value=1, max_value=pos_inf)
-    result = tvm.arith.int_set.union_lower_bound([set_0, set_1])
+    set_2 = tvm.arith.IntervalSet(min_value=pos_inf, max_value=neg_inf)
+    result = tvm.arith.int_set.union_lower_bound([set_0, set_1, set_2])
     assert result.min_value.same_as(neg_inf)
     assert result.max_value.same_as(pos_inf)