The sound change from Latin /f/ to Old Spanish and Gascon /h/ has often been attributed to stratal influence from Basque. The motivation would be that Old Basque lacked /f/, and instead had a phoneme /h/, with which bilingual speakers replaced it when speaking in Romance. However, this hypothesis presents several difficulties. Most importantly, Navarrese Romance preserves Latin /f/, and in Basque itself, /f/ is adapted as /b/ in loanwords from Latin and Romance, not as /h/. Here we will argue that Old Basque had neither /f/ nor /h/. Instead, modern Basque /h/ derives from older */χ/. Medieval data will play an important role in establishing this. This hypothesis explains a number of morphophonological alternations, as well as some puzzling aspects in the treatment of aspiration in Romance borrowings, and it also makes it more difficult to hold to the stratal hypothesis for the Romance change /f/ > /h/.