This study focuses on curriculum adaptation in Turkey where the school system is highly centralised, high schools are quite hierarchical, regional differences are intense, and a single, renewed curriculum is put into practice in all types of high schools that enrol students via high-stakes tests, unlike the Western context. Specifically, this multiple case study examines how and why five high school mathematics teachers in different types of Turkish rural high schools adapted the state-mandated curriculum. Interviews, observations, and documents were used to look for patterns and causes of adaptation. Findings revealed that although teachers do not disclose it in their plan, due to their lack of autonomy, they adapt the curriculum according to the perceived needs and attributes of students to cross over the 'brick wall' built by the Ministry of Education. Also, all the teachers use the same adaptation patterns that are 'omitting'; 'creating'; 'replacing'; 'changing the amount of time'; 'superficial teaching'; and 'using different sources/materials'. The reasons for adaptation and commonly used patterns are related to the perceived student profile, regulations, and nation-wide high-stakes tests. Consequently, suggestions are made to ensure curriculum does not end up as just written documents, and to prevent high-stakes tests from steering the instruction.