This study examines an interlanguage in which Moroccan learners of Dutch use non-thematic verbs in combination with thematic verbs that can be inflected as well. These non-thematic verbs are real dummy auxiliaries because they are deprived of semantic content and primarily have a syntactic function. Whereas in earlier second language (L2) research only patterns with "be" were found for learners of three Germanic languages with various first language (L1) backgrounds, an alternative dummy auxiliary pattern was observed with "go" in the data of the Moroccan learners of Dutch. We argue that the auxiliary pattern with "go" is bootstrapped by the unique similarities between Dutch (L2) and Arabic (L1). The emergence of dummy auxiliaries precedes movement of the thematic verb, and it turns out that adult L2 learners can be plainly focused on expressing syntactic properties. (Contains 19 notes and 5 tables.)