Celestina scholarship has devoted many pages to the influence of Cárcel de amor on the Tragicomedia de Calisto y Melibea. However, this is not the only work by Diego de San Pedro that has left trace in the Tragicomedia. Actually, his religious writings La Passion trobada and Las siete Angustias de Nuestra Señora could have played an important role in the composition of the tragic ending of Celestina. In this article, I will enumerate the arguments in favour of the influence of the religious writings of Diego de San Pedro on Celestina, both textual and structural. Moreover, I will offer a brief explanation on why and how San Pedro's religious poems were chosen to build the final acts of Celestina.