If after performing ṣalāt al‑iḥtiyāṭ one realises that the deficiency in the number of rakʿahs in his prayer was the same as the number of rakʿahs in his ṣalāt al‑iḥtiyāṭ – for example, for the doubt between three and four rakʿahs, he performs one rakʿah of ṣalāt al‑iḥtiyāṭ and later realises that he had performed three rakʿahs – in such a case, his prayer is valid.