This article relativizes the thesis that Benjamin Constant's thought is a direct antecedent of Isaiah Berlin's distinction between positive and negative freedom. According to that position, there would be a clear similarity between Berlin's Two Concepts of Liberty and Constant's The Liberty of Ancients Compared with that of Moderns. Firstly, I talk about the way in which Berlin refers to Constant in order to account for the latter's distinction. I then examine a relevant difficulty for Berlin's proposed affiliation: Constant's republican tone. Thirdly, I discuss Constant's thought to determine the role played by this republican tone, which is indispensable to measure his differences when compared with Berlin. Finally, I conclude with some reflections on the relationship between the two authors.