Academic writing requires both style and grammatical correctness; however, efforts in improving the quality of English academic writing by non-native students have been focused on grammar. Structures observed in this study were grammatically correct, but considered unnatural in academic writing genre. This research involves a group of non-native English speaking students who were assigned to submit two different kinds of writing to an online repository: a research paper abstract and a free writing article. A survey to understand the sources of English exposure is also conducted. The objectives of this study are to describe unnatural sequences/Multi Words Units (MWUs) used by the students and to identify the motives of using such sequences. The tools for corpus processing used are "Unitex" and "Antconc." Corpus of Contemporary American English and British National Corpus are also used as reference corpora for English while the SEAlang Indonesian Corpus is used to validate the influence of first language (L1). The analysis of these sequences with comparison to reference corpora indicated the influence of spoken English and students' L1 (Indonesian). This corresponds to the results of the survey that most of the students are exposed to English mostly via spoken, and non-academic sources (songs, movies, social media, etc).