The article investigates the linear-syntactic properties of clitics in a series of Bulgarian dialects that are or were in contact zones with the Romanian-speaking population. The most distinctive feature of these dialects is the initial position of clitics. The essential factors determining the differences between the dialects under study are the conditions under which language contact occurs/occurred, its permanence and duration. These factors influence not only the optionality vs. stable variation in the realisation of the initial position, but also the extension of the paradigmatic and syntactic properties of clitics in the initial position. The question is raised as to what level of interference allows the clitic initialisation parameter to be copied from the donor language. The material of the Greben dialect on the territory of Bulgaria, with a low degree of contact-induced change, has shown that this is possible even without other grammatical consequences of contact. The features of the Bulgarian language that contribute to the ease of repealing the Tobler-Musafia law are analysed.