A data storage circuit includes memory, an error correcting code (ECC) storage circuit, and control circuitry. The memory is configured to store a data value comprising a plurality of fields. Each of the fields is independently writable. The ECC storage circuit is configured to store an ECC value corresponding to the data value. The control circuitry is configured to receive a field value to be written into one of the fields, and store the field value in the one of the fields by writing only the field value to the memory. The control circuitry is also configured to retrieve the ECC value from the ECC storage circuit, compute an updated ECC value based on the ECC value retrieved from the ECC storage circuit and the field value, and store the updated ECC value in the ECC storage circuit.