Language errors play a crucial role in language learning and teaching. Using Indonesian in ways that exceed its standard communicative and linguistic norms is considered improper. Such deviations indicate a misuse of the language, whether orally or in writing, as they do not adhere to the established communication parameters and grammatical structures. The objective of this investigation is to scrutinize linguistic inaccuracies present in in the book titled Kuliah Muhammadiyah Gerakan Tajdid. The book titled Kuliah Muhammadiyah Gerakan Tajdid: Pendekatan Ideologis, Historis, Organisatoris, dan Analisis was written by H. Anhar Anshori, M.S.I., Ph.D., and published by UAD Press. This book provides a comprehensive description of Muhammadiyah as an Islamic movement, the da'wah of enjoining good and forbidding evil, and tajdid (renewal). This book is often used as an important reference for the Muhammadiyah course at various Muhammadiyah universities. This research adopts a descriptive qualitative methodology, employing an observational approach. The findings indicate the presence of 12 distinct types of orthographic errors. These encompass issues related to letter usage (specifically, two errors involving capitalization), word formation (including four instances of non-standard or improperly formed words), and the incorrect application of punctuation marks (one error concerning the use of single quotation marks, three errors with hyphens, and one error in semicolon usage).