diff --git a/barretenberg/cpp/src/barretenberg/vm2/tracegen/lib/lookup_into_p_decomposition.hpp b/barretenberg/cpp/src/barretenberg/vm2/tracegen/lib/lookup_into_p_decomposition.hpp
index 99e5d5c90ae7..4b7c91a16b8a 100644
--- a/barretenberg/cpp/src/barretenberg/vm2/tracegen/lib/lookup_into_p_decomposition.hpp
+++ b/barretenberg/cpp/src/barretenberg/vm2/tracegen/lib/lookup_into_p_decomposition.hpp
@@ -13,7 +13,7 @@ template <typename LookupSettings> class LookupIntoPDecomposition : public BaseL
     uint32_t find_in_dst(const std::array<FF, LookupSettings::LOOKUP_TUPLE_SIZE>& tup) const override
     {
         const auto& [radix, limb_index, _] = tup;
-        size_t radix_index = static_cast<size_t>(radix);
+        size_t radix_index = static_cast<size_t>(uint64_t(radix));
         uint32_t row = 0;
         for (size_t i = 0; i < radix_index; ++i) {
             row += static_cast<uint32_t>(get_p_limbs_per_radix()[i].size());