We revisit voluntariness of voluntary export restraints (VERs) in a differential game model of duopoly with sticky prices. We show that a VER set at the free trade level has no effect on equilibrium under open-loop strategies while the same policy results in a smaller profit for the exporting firm, i.e. it is involuntary under a non-linear feedback strategy. Moreover, we prove an extended proposition of Dockner and Haug (1991) on voluntariness of VERs under a linear feedback strategy. Copyright 2010 The Author. Journal compilation 2010 Blackwell Publishing Ltd/University of Adelaide and Flinders University.