Linguistic similarities increase cooperative behavior between people, while linguistic differences can reduce cooperativeness, and even promote aversion towards outsiders. This may not only be true for sharing the same native language, but also for more subtle similarities such as using similar syntactic constructions. In our experiment, participants communicated with two interaction partners (which were in fact standardized chat bots), one of which syntactically aligned their language with the participants and one of which didn’t. Afterwards, participants decided with which of the two partners they would like to play a cooperation game that determined the financial bonus that they would receive for participation. Against our predictions, linguistically aligned communication partners were not preferred as cooperation partners over non-aligned communication partners. This suggests that formal linguistic similarity may be less relevant for the outcome of negotiations than previously expected, and has real-life implications for conflict resolution, especially in intercultural communication settings.