This corpus study compares the use of Danish prepositions in the writing of L1 users of Danish to that of L2 users of Danish (with English as their L1). It examines to what extent non-standard usage is a specific L2 phenomenon and to what degree the challenges with prepositions are shared between the L1 and L2 group. We analyze the distribution and characteristics of non-standard usage involving four frequent Danish prepositions: til ‘to’, i ‘in’, på ‘on’, and for ‘for’. The results show that L2 texts are characterized by a larger share of non-standard tokens and by confusion of prepositions and non-prepositions. Yet, both L1 texts and L2 texts have non-standard usage and both have possible English calques. Based on the similarities between the two groups, we recommend that future studies include naturally occurring L1 production as a baseline for describing characteristics of L2 production.