Computational thinking (CT), the thought processes used in solving computational problems, has been added to the educational standards in many countries around the world. However, this new content presents challenges around preparing teachers to integrate computational thinking robustly into the STEM disciplines. In this proceedings, we conduct a preliminary investigation of the challenges of preparing secondary pre-service teachers to integrate computation into their subject teaching. We present data from interviews with three pre-service secondary subject teachers in the KURT at UiO to highlight two challenges of pre-service teacher (PST) preparation: first, (1) the computation learned in upper division subject courses does not directly translate to the computational thinking that they will be teaching their future students; and (2) in their pedagogy courses, they learn about computational thinking but are not able to translate that into their practice of teaching. We consider the implications of and solutions for these challenges on pre-service teacher preparation.