| diff --git a/ntt_parameters.h b/ntt_parameters.h | |
| index c3da197..55671ec 100644 | |
| --- a/ntt_parameters.h | |
| +++ b/ntt_parameters.h | |
| @@ -168,7 +168,7 @@ struct NttParameters { | |
| ~NttParameters() = default; | |
| int number_coeffs; | |
| - std::optional<ModularInt> n_inv_ptr; | |
| + absl::optional<ModularInt> n_inv_ptr; | |
| std::vector<ModularInt> psis_bitrev; | |
| std::vector<ModularInt> psis_inv_bitrev; | |
| std::vector<unsigned int> bitrevs; |