A memory controller includes an interface and circuitry. The interface is configured to communicate with a memory device, which includes multiple memory cells, and which applies refreshing to the memory cells by repeatedly inverting data stored in the memory cells. The circuitry is configured to store input data in a group of the memory cells, to read the stored input data from the group of the memory cells to produce read data, the read data has an actual polarity that is either un-inverted or inverted due to the refreshing of the memory cells in the group, to analyze the read data for identifying the actual polarity of the read data, and to recover the input data from the read data based on the identified actual polarity.