diff --git a/ets2panda/compiler/lowering/ets/lambdaLowering.cpp b/ets2panda/compiler/lowering/ets/lambdaLowering.cpp
index 1d45f1c3716b04eb2c97fd3c207e1a1601c32c91..27dbc5794a8d8c5b4e4a4486bcf107271bf82458 100644
--- a/ets2panda/compiler/lowering/ets/lambdaLowering.cpp
+++ b/ets2panda/compiler/lowering/ets/lambdaLowering.cpp
@@ -1513,7 +1513,7 @@ static ir::AstNode *TransformTupleSpread(public_lib::Context *ctx, ir::CallExpre
         ArenaVector<ir::Expression *> tupleElements(allocator->Adapter());
         for (std::size_t idx = 0U; idx < arg->TsType()->AsETSTupleType()->GetTupleSize(); ++idx) {
             auto *ident = genSymIdent->Clone(allocator, nullptr);
-            auto *number = allocator->New<ir::NumberLiteral>(lexer::Number(idx));
+            auto *number = allocator->New<ir::NumberLiteral>(lexer::Number(static_cast<uint64_t>(idx)));
             auto *indexed = util::NodeAllocator::ForceSetParent<ir::MemberExpression>(
                 allocator, ident, number, ir::MemberExpressionKind::ELEMENT_ACCESS, true, false);
             tupleElements.push_back(indexed);