In standard Dutch, the plural suffix -enis homographic and homophonic with the linking suffix -en(boek+en“books”,boek+en+kast“bookcase”), both being pronounced as schwa. In Frisian, there is neither homography nor homophony (boek+en“books”, pronounced with syllabic nasal;boek+e+kast“bookcase”, pronounced with a linking schwa). Seeing that many areas of Frisian grammar are subject to interference from Dutch, we investigated whether Frisian-Dutch bilinguals exhibit interference from Dutch with respect to the linking suffix during Frisian speech production. Two types of Frisian-Dutch bilinguals emerged: Speakers who had Dutch as their first language tended to maintain the Dutch system of homophony between plural and linking suffixes when speaking Frisian, by using the Frisian plural as a linking morpheme. Speakers who had Frisian as their first language often maintained the Frisian system of no homophony when speaking Frisian. The implications for morphological theories are discussed.