We consider the effects of a one-sided price regulation of one of two complementary inputs. The provider of the regulated input is a domestic firm, while the provider of the other input is a foreign firm. This describes the market structure for several digital information and communication services, where the regulated input is access while the non-regulated complementary input is content. We show that one-sided regulation may have negative welfare effects compared to a free market economy, unless the regulator has a first-mover advantage. In the latter case, regulation is welfare enhancing regardless of whether the foreign input provider uses linear or non-linear wholesale prices.