diff --git a/src/transform/merge_shared_memory_allocations.cc b/src/transform/merge_shared_memory_allocations.cc
index 4b0c07a7e..ce23a1af4 100644
--- a/src/transform/merge_shared_memory_allocations.cc
+++ b/src/transform/merge_shared_memory_allocations.cc
@@ -283,7 +283,9 @@ class SharedMemLinearAccessPatternFinder final : public StmtExprVisitor {
     } else if (op->attr_key == "kWarpSpecializationScope") {
       IfThenElse body = Downcast<IfThenElse>(op->body);
       this->VisitStmt(body->then_case);
-      this->VisitStmt(body->else_case.value());
+      if (body->else_case.defined()) {
+        this->VisitStmt(body->else_case.value());
+      }
     } else {
       StmtExprVisitor::VisitStmt_(op);
     }